Umka 1.3.1

• for..in now allows accessing collection items by pointer
• Error handling:
  • error() is removed
  • exit() now accepts an error code returned to the OS and an optional error message
  • umkaRun() and umkaCall() now return an error code (0 on success)
  • umkaAlive() is added to check if the interpreter can still execute umkaRun() or umkaCall()
  • std.Err, std.error(), std.exitif() are added for graceful error handling
• Unicode support:
  • printf() on Windows fixed
  • Locale parameter in umkaInit() is deprecated
• Bytecode optimizations
• Cyclic import detection
• Bug fixes