native api requests

[velkyel]

Hello,

finish please native interface:

• _vecAdd() function in tests/native/example2.c (native object from slot)
• example how to call pk function from c/c++ with parameters (pkRunString() is not enough)
• list api

thank you

[ThakeeNathees]

I've just implemented the native instance "ffi", and completed the example2.c which you can find #229, Apis for other types (string, list, map, functions..) is just a matter of writing wrappers for them including function calls, which I'll write them soon.

Additionally, I've been planning about native extensions -- importing shared libraries *.so *.dll as pocketlang libraries (like Lua, Ruby, etc do) "ffi" binding generator script for that can be found at : https://github.com/ThakeeNathees/pocketlang/blob/master/scripts/generate_native.py.