Fix function naming of functions inside traits

[rodrigo-pino]

Functions inside WarpMemory, are being called this way:

let x = warp_memory.get_or_create_id(...)

Because, currently warp_memory is invisible to the solidity AST, the warp_memory. prefix is included in the naming. So for the example above, get_or_create_id is actually called warp_memory.get_or_create_id.

Two possible solutions are including WarpMemory to the AST, and making all function calls part of a member access, or keep it hidden. The second one is fastest, and easy (it would be cool to implement it in a non hacky way)