Various updates
Various updates

These updates were required to address issue #49:

* Changed the source_re definition to include capitalization of Cannot.

* Added the root directory to the set of directories searched for GCOV files.
  This is necessary to correctly capture data for symbolic paths.

* Eliminated non-code lines from the text summary.  This might make this
  summary more verbose, but it makes it more accurate for the user.

cloudsmith-io/gcovr,thatguystone/gcovr,thatguystone/gcovr,thatguystone/gcovr,kevincon/gcovr,cloudsmith-io/gcovr,kevincon/gcovr,thatguystone/gcovr,cloudsmith-io/gcovr,kevincon/gcovr,cloudsmith-io/gcovr,kevincon/gcovr