Grow throbbers with each throb.
Fixes for AIR testing.
Throbbers remove themselves after they've reached max level.
Clicking an object no longer spawns a new one.

Overridding destroyObject so that self-destroyed throbbers also get removed from our throbber set.
Start with two throbbers on the board and add 2 more each throb.
Shorten the testing static throb time.
Enforce the max throbber count.
Fix placement, now that throbber size is variable.
Polish up the throbber levelup radius change.