Added some P4Python-based Perforce triggers.
P4Triggers.py is the based class for change trigger in Python modelled on
Tony Smith's Ruby trigger with the same name.
CheckCaseTrigger.py is a trigger that ensures that no-one enters a file
or directory with a name only differing by case from an existing file. This
trigger is Unicode aware and uses Unicode-comparison of file names, so it
can be used on nocase-Unicode based Perforce servers, which cannot catch
the difference between, say, "�re" and "�re" at the moment.
clienttrigger.py is a simple trigger that modifies the option "normdir" to
"rmdir" for new client specs only. It is meant as a template to create more
complex default settings like standard views.