Added new sh checker: checkbashisms.
Removed unsafe tcsh checker.
Typo in cpp/gcc checker.
Merge pull request #579 from lcd047/typo

Fix for #578
Use and adapt to more recent checkbashisms.pl. Some refactoring.
Try to cope with older versions of jshint.
Merge pull request #582 from lcd047/jshint_args

Fix for #581
Merge pull request #574 from aswna/master

Added new sh checker: checkbashisms.
sh/checkbashisms: remove unneeded l: variable prefixes