Fix ClassCastException for malformed plugin.yml. Fixes BUKKIT-3563

If the plugin.yml gets loaded but wasn't in the form of a map, the
server would crash. This safely checks to see if it can be cast,
throwing invalid description if it cannot.
EMC POM Changes
Measure the duration of the entire timings run.
Add CustomTimingsHandler for adding new CraftBukkit custom timings
Make BlockFromToEvent default cancel if the flow would trigger a chunk load.
Timings improvements.