Add support for structs/unions defined in structs/unions
Added test for anonymous structs and unions
Removed time and added a hash based on filename, line and column for creating a unique struct id
Sorting enumerations and generation of consts for enumfields with the same value + test
Made the code more robust and detect nkPrefix as number (-1 or +4) for enum sorting. Added also a new test for enums.
Merge pull request #1260 from enurlyx/structs-in-structs

c2nim -> Support for anonymous structs/unions