* added highly experimental startup option `--query.parallelize-gather-writes`
Turning this option on will enable the `parallelize-gather` AQL
optimizer rule for certain write queries. This option is `false`
by default.
The feature is highly experimental and should not be used on a
production system. The option is therefore also hidden.
* parallelize certain write operations in AQL
* remove unneeded _vocbase
* remove unneeded _vocbase
* added startup option and tests
* 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
Jan
Jan Christoph Uhde
Frank Celler
Vasiliy
jsteemann