* added missing return statements
* only spend up to 10 seconds for initially fetching the list of collections in arangosh
fetching the list of collections is a blocking operation, and the default timeout for this is very high.
If the server is blocked by whatever reason, then the shell is unusable until the collections list request returns.
To avoid this, the initial request is limited to 10 seconds, so the shell can be used afterwards.
* if an index cannot be used for sorting, its sort
cost was previously returned as 0. this will in fact favor
indexes that can be used for filtering but not for sorting
over indexes that can be used for both.
this change is to report the sort cost for indexes that
cannot be used for sorting to n * log(n), where n is the
number of documents that optimizer expects to come out of the
index after filtering
* 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
* fix a memleak in `db._collections()` on coordinator when there are no access rights to a collection
* fix some memleaks on arangosh shutdown
* added missing TRI_V8_TRY_CATCH_BEGIN|END blocks