Remove unused code
More asserts
Bugfix: need a WORK hashmap per remote jvm
bugfix: lazyarraychunk can only make chunks on the home node

because we need the mem-manager caching/replication info to be correct.
Debated, and didnt go to the place of having a remote node make the lazy
chunk, then tell the home that he as a replica.
bugfix: a TaskGetKey invoke can call lazyarraychunk, which makes a nested TGK

Nested TGK's can deadlock... so make the nested TGK of the array header run
at a higher priority to dodge the deadlock (priority asserts caught this one!).
Pass priorities into and around TGK's logic.
Bug fix: nested remove of array chunks can go straight to DKV.remove

Otherwise the nested UKV.remove calls get calls lazyarraychunk making the
very chunk we are trying to delete!
Simple test using FileIntegrityChecker and parsing covtype

Exposed recent issues with lazyArrayChunk.
Not very fast to run, since covtype is relatively large