move library code to framework

- Create SwiftForthKit framework and move all library code there.  The
  SwiftForth target now only contains the REPL code and links against
  the framework.

- Add public specifiers to export API from framework.
cleanup xcode schemes

- Remove personal stuff.

- Remove obsolete SwiftForthTests scheme.

- Run SwiftForthTests when testing and current scheme is SwiftForth.

- Update .gitignore to filter out all personal stuff.