[Vala] try/catch concepts

[pancake <pancake youterm com>]

I've been thinking a bit on this post.. and I agree with it that 
exception handling via try/catch hides the proper control flow of the 
program and can result in problematic situations.

  https://groups.google.com/forum/#!topic/nodejs/1ESsssIxrUU/discussion

as far as GObject follows a proper approach, and Vala just adds some 
sugar on top of it, we could add a way to manager exceptions in a more 
specific way. but I don't know which would be the right way to do it.

I just want to share this thing with you and get some feedback about 
what you think it's ok for a language that aims to avoid common 
programming errors and keep the code easier for maintainance.

--pancake