- further fixes of inccorect overflow errors for int (and long on LLP64 systems) * prev commit had bugs * added overflow tests for also int, long, long long (for both, lp64 and llp64) - while at it, fixing a reference leak when not using python with utf8 caching

* PowerPC/Mac OS X 10.4: Building Universal Binaries are broken.. in particular 
  the as for i386 assembler. 
  Workaround for PowerPC users: install with "--no-multiarch" or use prebuilt 
  binaries built on OS X >= 10.5.