Transition no longer modifies given options.

This allows the API to report back the Python structure that was inserted, and generally avoids problems. A tiny amount of additional memory may be used, if dictionaries actually shrink in practice.
Moved API landing page to separate file.

The file is currently read on each API request, which is not ideal but the number of hits on this particular page is expected to be very limited. The page now contains a little information and links to the GitHub page, Frack wiki and other relevant things. This is a first step to satisfying issue #5.