Transpile `#include` as `include!()`

[HKalbasi]

Currently, each generated file contains a copy of each header file it includes, so to make a change/refactor you will need to change multiple places, making changes harder than necessary. By transpiling C #includes to Rust include!, it will become much easier to refactor without losing the C semantics (which will probably happen by using mod and similars).

[kkysen]

This is a good idea.

[pitaj]

Duplicate of #1050 ?

[kkysen]

Duplicate of #1050 ?

This is a bit different I think.

[pitaj]

They essentially describe the same idea, the only difference is that this one suggests using include!() to implement it.