Implementation of newer type-checker rules

New way of connecting Constraints, changed Syntax, changed Types structure. Removed incompatible Parser & Interpreter modules (the latest commit with Parser & Interpreter modules more or less compatible with the then current Syntax & Types is https://github.com/miconi/lucretia/tree/642fbfe0a4d6c907f021bb14dd4b3eae941b11bf/src/Lucretia).

Implemented & tested rules: var, const, new, bot, acc, updt, let, cnstr <, typ <, weakening &
renaming, fdcl & fapp. Work in progress — if rule. Rules to be implemented later: ifhttr, ifhttr*, E/\i, I/\.