Fixing the funny bug in operator %
New set of tests. Loops and a few more about arithmetic operations
Fix of error in the way of freeing registers. It was affecting the
compilation when many basic block were involded
Two errors fixed:

1 - The semantic of iload is not copy reference but copy value to a new
location. It is a bit hard to undertand for me but the jvm's guys use this fact to
implement ++. For instance: a = i++ is encoded as iload_i, iinc i,1,
istore_a.

2 - operator if_icmpne implemented. Refactoring to unify with ifjne
some additionals comparators
adding operator ishl and ishr