* Make isRestore work in the cluster.
This covers sharded collections with default sharding and non-default
sharding.
* always use locally generate revision ids for storing and looking up documents
* do not use V8 variant of AQL functions in early optimization stage when a C++ variant is available
* additionally, simplify AQL function definitions and aliases
* warn when more than 90% of max mappings are in use
* added C++ variant of replication catchup
* added `--log.role` option
* updated CHANGELOG
* removed non-existing scheduler.threads option from config
* removed useless __FILE__, __LINE__ invocations
* updated CHANGELOG
* allow a priority V8 context
* remove TRI_CORE_MEM_ZONE
* try to fix Windows errors & warnings
* cleanup
* removed memory zones altogether
* exclude system collections from collection tests
* removed delete call
* cleanup
* lower cpu activity of log thread too
* fix log messages
* do not enter threads into unordered_set, as it is unneeded
* do not compile in calls to disabled plan cache
* moved AQL regex cache from thread local variables to a class of its own
* more sensible thread creation and destruction
* simplify index API a bit
* fix fulltext index removal performance, simplified code
* updated CHANGELOG
* fix hanging test
* try to fix shutdown problem
* improve fulltext query performance
* fixed duplicate var
* removed obsolete code
* fix some shutdown races
* do not call ensureIndex that often