SurvivalFly: Add tag lowfoodsprint for debugging purposes.

This tag is added if the player is sprinting but the food level has
dropped. Not sure this can actually be the case.
[Safety commit] Prepare better mod support for blockbreak (slowly).

Not yet in place, but setting up new package structure to split off some
things from BlockProperties. Likely not final.
Update supported versions of MCAccessBukkit.
Move auxiliary code.