Dev: refactor main OtherDrops class - no functional change

* pull "performDrop" and associated methods into own class "SectionManager"
* extract methods in onEnable for easy of reading
* some general Eclipse cleanup
Dev: refactor DropRunner - no functional change

* just broke up monolithic "run()" method into more manageable chunks.
Dev: 1.6.1 - add unimplemented method in PlayerWrapper