* Added info on focus/ignore/show/hide to legend on graphs

* Made separate function for formatting filters in legend

Previously we were showing filenames together with function names
when generating reports at function granularity. This was an attempt
to provide more information to the user, but it clutters the output.
Also, in cases where a function is associated to multiple files
(eg template instantiations in C++), keeping the filename may prevent
us from combining nodes from the same function.

Will stop keeping filenames at the default function granularity, and will
remove the "functionnameonly" option which was previously providing this
functionality.

By default hide entries in the comment field that starts with #, and
add a "comments" command to show all comments.

When reconciling samples, cleanup file paths to allow functions to be
combined if their source filenames match after cleanup (eg "src.cpp" and
"./src.cpp").

Also clean up existing uses of filepath to avoid passing empty strings
to it: filepath.Base("") returns "."

Also update the build instructions to use go get