Get all logs in Tree Feller, and optimize performance

Tree Feller has been shown, both anecdotally and with timings, to put a strain on the server, and therefore is worthy of the effort of optimization.
Prior to this change, on jungle trees, Tree Feller would take around 20-40 milliseconds to process a Jungle Tree after the JIT kicked in, and around 15-25 milliseconds for a normal tree.

Additionally, logs would be left up in the air for jungle trees.

After this change, Tree Feller takes 2-5 milliseconds on normal trees, and 10-15 milliseconds on jungle trees, and no logs are left up in the air.

The method taken by this change is as follows: