Drastically reduce number of string related memory-leaks

Fixed a bunch of errors introduced earlier ( labels not printed in output, "goto" comments not printed correctly )
Enhanced Const integer printing to convert 0xFFFFFFFF to ~0x1 where appropriate (the rule is "smaller code wins" ).

TypeTest leaked 30MB of memory before this - now 'only' 6

Most of the changes were replacing the std::string/const char *  with QStrings
Merge pull request #21 from nemerle/leak_be_gone

Leak be gone !