There have been several requests on the mailing list or the
bug tracker to support parsing warnings for alien compilers
(sometimes slightly modified GCC).

Instead of natively supporting every compiler, users of less
frequently used compilers should use the custom parser to
parse errors and warnings.

The output channel filter for error and warning parser allows
to scan standard output, standard error or both channels.

Also added tests for twisted capture positions.

Task-number: QTCREATORBUG-11003
Change-Id: I5a5bd6f88cf21cde1c74962225067d4543693678
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>