Add support for referencing arbitrarily deeply nested controllers

- Controllers can now be referenced like this:
  + `Very::Deeply::Nested::controller' (class method)
  + `Very::Deeply::Nested#controller' (instance method)
- It works with all mapping methods (`gget'/`ppost'/`mmap'/...).
- `README.md' has been updated accordingly. Read it for further
  details.
Enforce the 80 column limit on `README.md'

- This will make future diffs more pleasant to read.
- Also, acknoledge the existence of the new
  `rroute_call_nested_controller_from_string' method.
Bump the version number