#54 Added exit function to os namespace

Fixed #54
#37 Fixed resolving of constant identifiers

Resolving identifiers in binary expressions was broken, especially for
bit masks.

A side-effect of the fix is that any lang::constant reference will now
always assume the type of its enumeration.

Fixed #37
Merge pull request #55 from Seldomberry/SanderMertens

Sander mertens
#56 Replaced ':' in key-value pairs with '='

Fixed #56
Merge pull request #57 from Seldomberry/SanderMertens

#56 Replaced ':' in key-value pairs with '='
#27 Expanded bitmask test case and fixed issues

Added conversion routines for bit masks. Also fixed an issue where
binary expressions would not be evaluated (and folded) in the first
pass, causing issues when a mask was part of an initializer.
Merge pull request #59 from Seldomberry/SanderMertens

#27 Expanded bitmask test case and fixed issues
Merge branch 'master' into jleeothon