* Add support for tag units

Updated tests for adding tag units

* updated proto docs to describe tag units

* fixed formatting

* added additional test

* require specific units for graph tag to be recognixed

* updated tests and formatting

* Fixed formatting

* Fixed style error

* modify proto_test to be sure tag units not overwritten

* Clarified label docs

* call legacy profile memory allocations size, not byte

* updated tests to call bytes tags in legacy profile size

* Revert "updated tests to call bytes tags in legacy profile size"

This reverts commit 9289378af2.

* Revert "call legacy profile memory allocations size, not byte"

This reverts commit 6b18973562.

* Updated so units not modified when profile written out

* Fixed formatting errors

* Removed field for inferred numeric label units from profile

* Modified profile String() output

* fixed formatting error

* changed name of function used to identify units for numeric labels

* Refactor String() for profile

* Modified for clarity and address comments

* renamed function for clarity

* Made numeric label units field seperate in profile

* Modified test

* Refactored identifyNumLabelUnits()

* Updated comments

* Fixed formatting error

* Addressed comments

* Fixed style error

* clarify comment

* Refactored to address comments

* addressed comments

* addressed comments

* addressed comments

* Remove unnecessary line of code

* Fixed style error

* Modified variable type to have []string value

* added repeatableStringKind

* modify repeatableStringKind to actually handle multiple values

* Modify applyFocus to work with multiple values for tagfocus/tagignore

* Modify applyFocus to work with multiple values for tagfocus/tagignore

* Modified CompileTagFilter to handle tag filters of the form -tagfocus=key1=val1

* Modified StringList

* add testing for compileTagFilter

* fixed typo

* fixed code style error

* Revert "fixed code style error"

This reverts commit 0b1826c163.

* Revert "fixed typo"

This reverts commit 2593652bd0.

* Revert "add testing for compileTagFilter"

This reverts commit 152d7b0363.

* Revert "Modified StringList"

This reverts commit b57d35a762.

* Revert "Modified CompileTagFilter to handle tag filters of the form -tagfocus=key1=val1"

This reverts commit ebe1e344bf.

* Revert "Modify applyFocus to work with multiple values for tagfocus/tagignore"

This reverts commit 3b62091b67.

* Revert "Modify applyFocus to work with multiple values for tagfocus/tagignore"

This reverts commit 7172159cd3.

* Revert "modify repeatableStringKind to actually handle multiple values"

This reverts commit abb1e3ec4b.

* Revert "added repeatableStringKind"

This reverts commit 8b8e4e76fc.

* Revert "Modified variable type to have []string value"

This reverts commit 5f213dc4d1.

* added support for filtering by specific tags

* Fixed formatting problems

* Updated variable name for clarity

* Added test cases for tag filtering

* Update tagfocus and tagignore description

* Fixed formatting error

* Updated docs to explain new tag filtering

* Updated docs to clarify tag filtering

* Updated docs to clarify tag filtering

* Updated docs and help comments for tag filtering

* Updated docs for tag filtering

* Update pprof docs for tag filtering

* Update tagfocus and tagignore help descriptions

* Update tagfocus and tagignore descriptions in docs

* Update tagfocus and tagignore descriptions in docs and help

* Updated tagfocus and tagignore descriptions in docs; added TODO for regexp matching

* Updated tagfocus and tagignore descriptions in docs

* Modified docs fo tagfocus for clarity

* `git ls-files -- '*.go' | xargs gofmt -s -w`

* driver: unexport InternalOptions

This was an exported method that returned an internal type, so it's
unlikely that anyone depends on its presence.

* internal/binutils: remove newline in error string

golint reported: error strings should not be capitalized or end with
punctuation or a newline

* internal/driver: s/buildId/buildID/ per golint

* internal/elfexec: remove punctuation in error string

golint reported: error strings should not be capitalized or end with
punctuation or a newline

* internal/graph: correct comment

Found with golint.

* internal/graph: add method comment

golint reported: exported method Edge.WeightValue should have comment
or be unexported

* internal/report: remove newline in error string

golint reported: error strings should not be capitalized or end with
punctuation or a newline

* *: remove unused code

Found with honnef.co/go/tools/cmd/unused:

	internal/binutils/disasm_test.go:137:8: const objdump is unused (U1000)
	internal/driver/driver_test.go:353:6: type testProfile is unused (U1000)
	internal/graph/graph.go:838:6: func countEdges is unused (U1000)
	profile/proto.go:148:6: func encodeStringOpt is unused (U1000)

* *: simply code

Found with honnef.co/go/tools/cmd/gosimple:

	internal/driver/commands.go:471:24: should omit comparison to bool constant, can be simplified to !b (S1002)
	internal/driver/driver.go:163:5: should omit comparison to bool constant, can be simplified to !trim (S1002)
	internal/driver/driver.go:168:5: should omit comparison to bool constant, can be simplified to !focus (S1002)
	internal/driver/driver.go:172:5: should omit comparison to bool constant, can be simplified to !tagfocus (S1002)
	internal/driver/driver.go:176:5: should omit comparison to bool constant, can be simplified to !hide (S1002)
	internal/graph/dotgraph.go:213:34: should use make(map[string][]*Tag) instead (S1019)
	internal/report/report.go:1061:3: should replace loop with label = append(label, rpt.options.ProfileLabels...) (S1011)
	profile/proto.go:157:5: should omit comparison to bool constant, can be simplified to !x (S1002)

* *: correct mistakes

Found with honnef.co/go/tools/cmd/staticcheck:

	driver/driver.go:280:20: infinite recursive call (SA5007)
	internal/driver/driver_focus.go:54:11: this value of err is never used (SA4006)
	profile/proto.go:74:32: x | 0 always equals x (SA4016)

* Add linters to .travis.yml

Also update the build instructions to use go get