[TxMt] event commands

[Jan Sabbe]

I would like to be able to automatically run a script, when a certain 
event happens (such as, a file save), depending on the file-extension 
(and maybe also depending on the project).

For example, what I really like to do:
If I save a file that ends in .rb, I want to automatically run a 
command that does a "ruby $TM_PROJECT_DIR/test/unittests.rb". If it 
fails, it could send me a notification through growl 
(http://growl.info)