Source processing flow

A levelled overview of the operations fortran-src does on Fortran source.

Current (0.10.0)

1. Lex & parse (should be at same time)
2. ? TODO renaming? somewhere here, surely?
3. Run post-parse transformations
   • Includes running "implicit" type analysis, in order to disambiguate subscript syntax
4. Type analysis
5. Block analysis