Asserts and few more

This includes few minor improvements but primarily it includes additional assert macros. Honestly I kind of went overboard with this. I started using _Generic and it kind of became crazy. The problem is not that it is complicated but rather that it is completely written in preprocessor and uses a lot of preprocessor magic. C preprocessor is really not nice thing to use but just feel free to ask to anything that is not clear there as I am sure nobody here is well versatile with C preprocessor.