Support https with server certificate.

This change consists of two relatively independent parts, but they are
both about handling the granularity, so bundling them together.

First, in #415 there is a discussion that having a granularity mode by
source lines but with inlines hidden would be useful. The agreement is
also that adding `-linenoinlines` granularity would make the granularity
flags too messy (and they are already somewhat messy with `-addresses`
and `-addressnoinlines`. So, it was proposed to make `-noinlines` a
separate flag, which is what this change does. Note that the flag is now
pulled out of the granularity group so it's a bit of backward
incompatible change but I think it is acceptable. For the example in
issue #415 the user would now be able to specify `-list foo -noinlines`
to produce annotated source where the metrics from the inlined functions
are attributed to the calling inliner line.

With this change, I am also dropping the `-addressnoinlines` granularity
which is now supported as `-addresses -noinlines` combination. I
couldn't find any usage of this option at least internally at Google, so
I think it's safe to remove it.

Second, I am adding a separate `-filefunctions` granularity which groups
the data by both function and file. This is a follow-up to #110 from the
past where we changed the `-functions` granularity to not group by file
(it used to), and since then there was a couple of reports where using
just function name alone would over-aggregate the data in cases when a
function with the same name is contained in multiple source files (e.g.
see b/18874275 internally).

Also, make a number of assorted documentation and `-help` fixes.

* Remove stale docs, move useful ones.

* Rename the profile.proto documentation to README.md

* doc: make it obvious that host and port are both optional

* fix minor issue

* address comments

* 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

* Added an interactive web interface triggered by passing -http=port
on the command line.  The interface is available by visiting
localhost:port in a browser.

Requirements:
* Graphviz must be installed.
* Browser must support Javascript.
* Tested in recent stable versions of chrome and firefox.

Features:
* The entry point is a dot graph display (equivalent to "web" output).
* Nodes in the graph can be selected by clicking.
* A regular expression can also be typed in for selection.
* The current selection (either list of nodes or a regexp)
  can be focused, ignored, or hidden.
* Source code or disassembly of the current selection can be displayed.

* Remove unused function.

* Skip graph generation test if graphviz is not installed.

* Added -http port and the various modes of using pprof to the
usage message.

* Web interface now supports "show" option.

* Web interface automatically opens the browser pointed at
the page corresponding to command line arguments.

* Some tweaks for firefox.

* Handle review comments (better usage message, more testing).

* Handled review comments:

1. Capture and display errors like "Focus expression matched no samples".
2. Re-ordered buttons to match other interfaces.
3. Use UI.PrintErr to print error messages.

* Handle javascript code review comments (a bunch of cleanups).
Also added pprof binary to .gitignore.

Not all OSes have $HOME variable.
Use appropriate variables per OS.

Fixes https://github.com/golang/go/issues/18864