* 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
* implement transaction handler in c++
* add fake request object
* move general code into extra file
* improve error messages for RestJobHandler
* support cancel operation for async jobs with RestTransactionHandler
* fix integration test and add some optional debugging output
* fix returning of context
* fix error type
* fix code in cluster test
* remove unused variable
Wilfried Goesgens
Frank Celler
Jan
m0ppers
Jan Christoph Uhde