More string support, start of string formatting

- Compose string formatting WIP
- You'll be able to initialize strings with any type:
    string{vec3{1.0, 1.0, 1.0}}
    string{1.2}
    string{false}
    etc.
- You'll also be able to specify printf style formatting strings:
    string{"int: %d, float: %f", 4, 1.2}
- Support for this still underway
- Added StringInit and StringFormat Ast types
- Removed SCOPE token from parser, we ended up using '.' for scope
- Reogranized some stuff in BlockMemory.h, and broke it out into separate files
- Added $.print system api... still needs testing
- Added find_next_specifier to find and parse next printf style
  specifier in a string