Improve support for $if statements

[joachimmarder]

Currently all code in an $if statement is being removed. Propsed chnage: Inlcude code in $if but remove code in $else part, that would make code like this work:

const 
  cLength =
{$if CompilerVersion >= 22}
   500;	
{$else}
   250;
{$ifend}