Reworked context handling to be faster
Avoid some work when not tracking context
Removed unused variable `$match_word`
Removed unnecessary local copy of `$opt_regex`
Removed unnecessary local copy of `$opt_passthru`
Merge pull request #506 from sth/unnecessary-variables

Removed some unnecessary variables
Credit sth
Merge branch 'improve-context-handling' into dev

Conflicts:
	ack
Credit sth for helping with optimization
Add --hpp option

...to be able to dig only through C++ header files
Merge pull request #507 from sjaeckel/patch-2

Add --hpp option
Update for --hpp option.
Integrate patch for --ignore-dir=match:...

See also GH #42
Update changelog
Work on more tests for --ignore-dir
Add stub for --ignore-file testing
Use filter facility for --ignore-dir and --noignore-dir
Remove stringification overload for Filters

This is for debugging purposes anyway, and it messes with boolification
of filters
Remove redundant check

App::Ack::Resource::Basic::new can no longer return a falsy value,
since files are opened lazily.
Add IsPath filter

For implementing --ignore-dir in terms of relative paths