symbol: Don't name variable str ...

Identifiers starting with str are reserved by future C standards,
so change it.

lang: Replace symbol table with FNV hash ...

I don't want to deal with writing cross-platform thread wrappers at the
moment so we shall just switch to using hashing for symbols.

This isn't great as we can't iterate through existing symbols and it's
possible to collide these if you really want to, but it shall do.

lang: Run clang-format

lang: Add error handling functions

lang: Move symbols to own file