Add getters "len" and "rad" for CPS enhancement experiments

Also whitespace got auto-corrected

Also the FIXME comment for the new properties is important:

We should have proper whitelisting facilities in CPS
to overcome 'accidential' access to properties that weren't meant
to be used in CPS. Also, this could add a re-mapping of names
to getter methods (or getters). This would make the namespace
less crowded and allow a better names for he CPS user!
a comment typo and whitespace
add operators "polar" and "deg"

This is the experimental beginning of an CPS enhancement that will lets us
describe point positions as a distance plus an angle. This is an important part
to make our pen model more complete.