implement support for char and byte types

[davidnich]

• char: a unicode character - internally stored as the unicode character value (independent of character encodings)
• byte: a single unsigned char with the range 0 - 255

and possibly other integer types...

this can be done because:

• types are not keywords
• they can be implemented such that they are backwards-compatible with int and other types (ex: char values could be assigned to string as well, but not vice-versa)

This will allow us to implement efficient string and binary iteration, to be able to write more efficient scanners & parsers for example; ex: foreach char c in (str.charIterator()) { ... }

Depends on #1573