Remove REDIRECT_BASE, url, link and path

Never liked redirect_base, it smells bad.
Newest revision of HTTP allows relative Location so url becomes useless.
And then link and path falls too.
Rename s/renderFile/partial/ for familiarity
Change get to throw MethodNotAllowed

Rationale was to make it possible to class_alias to ease implementing
static pages. In practice this was bad idea and it makes more work to
implement resources that don't allow GET anyway.
Update to psr-4
Small refactoring, remove duplicate line
Add link()
Add layout option plus some scrutinizer improvements
Improve coverage
Replace uses of self with static
Open getLastModified to protected
Update README.md for v2
Normalize array usage in README.md
Merge with master
Refactor some more