Name resolution (and new tool, mh_lint)

[florianschanda]

Requires: #140

• [ ] find a sane way to deal with toolbox/builtins; ideally by being able to look at the installed MATLAB
• [x] new module m_sem, which is invoked after parsing
• [x] decide on a strategy on when to invoke it, especially if no project is configured
• [x] create new entry point (mh_lint) and documentation

Elements to resolve:

• [ ] classes (including separates), their methods and enumerations
• [ ] functions
• [ ] scope
• [ ] local variables
• [ ] globals and persistents

Types (or their lack thereof) are out of scope.