Possible bugs in tracer backend

[mcfx]

Recently, when I was trying to implement a tracer backend, I found some strange behaviors in your tracer backend.

I'm not sure which of them are bugs/features. So I just post all of them here:

• While calling a precompile contract, or an EOA, the gas and gasUsed seems incorrect.
  • Precompile example: 0xdeaea7b197b561b46265d9eb530a12bb82b1b9086c04eb9970f3a6fec815e800, path 0.3.0.
  • EOA example: 0xdeaea7b197b561b46265d9eb530a12bb82b1b9086c04eb9970f3a6fec815e800, path 0.12.
• failed to generate trace: 0x9c4ec73d10dfa27568451bdee845da387f84b9ec959507cf8170370c6273aeba.
• EOA has nonzero codehash: 0x66243f149a199f8697aac52a57594d3d8b08e35a06b15bc0f43e60c95d885ee3

By the way, I have published my tracer to openchain.go, it is possible to contribute code to openchain? Thanks.