Fix bug with exclude patterns and uncovered code

Fix of bug when LCOV/GCOV exclude patterns are used in
not executed code lines or not executed exception handling.
Merge pull request #24 from piotrdz/master

Fix bug with exclude patterns and uncovered code
Adding root path when opening HTML files.
Use -p option in print_html_report like print_text_report
Changes to resolve issue #22

Users have assumed that the -r option defines the
root directory for source files.  This is different from how '-r'
was originally used, which was simply to support filtering of files.

I decided to make this change of semantics, since we need to have a
root directory to correctly resolve symbolic links.
Merge pull request #26 from taichino/apply_sort_option_to_html_report

Use -p option in print_html_report like print_text_report
Changes to resolve #22
Merge branch 'master' of https://github.com/gcovr/gcovr
Clarifying semantics of filtering.

The options.filter data was being used with the
assumption that the filters were paths.  This is not
a good assumption, as is illustrated by the filter tests.