Some documentation for Registry and friends
Correct mistake in input registry documentation
Merge pull request #10 from githubnemo/documentation

Documentation
Merge branch 'master' into bc9337
Refactor the base of 9x37 properly

Make the original BC9037 abstract and let the actual implementations
implement the abstract `negated` method.

This way there is no fuss with getName/getFriendlyName and the
hierarchy is clear.
Remove experimental code

This leaked in here from another branch and has nothing to do here.
Remove collision detection code

This is not needed as this is for filtering targets and not
necessarily a station sign. While this can be used for stations,
it would be better to have an extra sign manage collisions and
rail blocks.