Please review my optimizations and code generation fixes

library:
- thrift's BYTE type is signed (so it is int8, not byte)
- asynchronous protocol is removed as irrelevant in go
code generation:
- safer constants using typed vars
- int64 consts over 2^32 dont blow up
- negative byte consts
- generated struct doesn't include type metainformation field to avoid metainfo creating for every instance
- map, list, set initializers didn't work
tests:
- use generated Work and CalculateArgs