Postfix Operators

[Tschipp]

Adds postfix operatorts ++ and --, which are compiled to (v.x=v.x+1;0)+v.x-1 and (v.x=v.x-1;0)+v.x+1 respectively. Test 'v.x = 1 + v.y++ + 2;': 'v.x=1+(v.y=v.y+1;0)+v.y-1+2;' still fails, because the parse order is incorrect.

[Tschipp]

Not sure why the previous two commits are also included here