refactor split_strategies 1 and 2
notes on coredump
add regionsByThread vector for better lookup
add SPLIT_STRATEGY_3

* prefer to shed regions with remote siblings
enable SPLIT_STRATEGY_3
implement dumb-merge

* merge siblings on lightest, if all available
* MERGE_STRATEGY_3
Add smart-merge, fix merge bug

* MERGE_STRATEGY_2
* fixed: merge would proceed all the way to the root
pass by reference
fix smart-merge to count reassigned players properly
scan-build instructions
API cleanup
Merge branch 'proj/dave-refactor' into proj/configurable-region-size

Conflicts:
	README.md