Revert two commits causing performance issues

Problem: Re-scanning and memory use in builds 2664+
http://youtrack.sk89q.com/issue/CMDHELPER-2938
Solution: Revert most of the commit that caused this issue. (except for a merge conflict)
Result: No more rescanning.

Problem: Extreme TPS drop caused by Minecart logic
http://youtrack.sk89q.com/issue/CMDHELPER-2943
This may actually affect all events, from what I can tell. In the case of minecart collision events, it consistently took ~16x longer to process.
Solution: Tracked down and reverted the commit that caused this issue.
Result: Performance back to normal.

I suggest we revert these as a temporary solution until the actual cause is fixed. The nature of these commits seem to be pretty safe to revert, but I'm not familiar with these systems.