Only do something if drive letters are defined.

If there are no drive letters defined (e.g. on Linux) then the regular
expression in the connectTo() function will also match links beginning
with ':', '/' or '\'.
Add a if condition that prevents registering a pattern for this plugin
if no drive letter is defined. This should prevent unnecessary load
created by this plugin, when it is not supposed to do anything.

Also this commit adds three tests for the aforementioned cases.
Remove unnecessary comments and add newline to EOF
Replace output-tests with parser-tests
Test plugin with existing mapping

The plugin reads hardcoded the mapping from its own conf/ dir, so I have
to some file swapping in order to use a custom mapping.php for my tests
and still preserve the original mapping.php.
Move flatten_array from global to a common class
Do not close php-files
Merge pull request #5 from micgro42/colonfix

Colonfix