Update gen_nim.py

[Angluca]

c: int uint = nim: int uint = x64:8byte, x32:4byte
c: type * = nim: ptr type or pointer = c:null, nim=nil
nim use byte or uint8 instead char not use char type name now,
But have cchar because is c type.

[Angluca]

I've change sokol-nim example/noninterleaved.nim

[floooh]

Hmm are these changes required because the most recent nim dev version breaks now? (or are they optional and just "nice to have")

I'd rather wait until nim stabilizes again to reduce the frequency of necessary updates to the bindings (I'm starting to think that the unsafeAddr => addr change was probably a bit too hasty, because it forces people to move from the stable version to the dev version).

[Angluca]

Nim will upgrade to stable v2.0 ( v1.6.x current now ) within the year.
There's a lot of changes and more new func in the new version
Things that will be dropped in the new version
Personally, I think it's best to change things in advance,
Because it's a lot of work to change things when you're have ( <= v1.6 ) project.

# These all version support ( v1.6 is use byte not char type name )
c: int uint = nim: int uint = x64:8byte, x32:4byte
c: type * = nim: ptr type or pointer = c:null, nim=nil
nim use byte or uint8 instead char not use char type name now,
But have cchar because is c type.