* 'engine-api' of https://github.com/arangodb/arangodb:
slightly adjust error messages
Fixing jslint errors
Add changelog from 3.1
Properly generate an error message during import
Fixed scannedIndex values in traverser tests. It did not report the correct number of lookups required after modification for new Storage-Engine
fixed issue #2429
issue #2427: change while into an if
don't fail when non-array, but simply ignore it
* 'engine-api' of https://github.com/arangodb/arangodb: (46 commits)
Merged RocksDBPathBasedIndex into RocksDBVPackIndex.
fix handling of externals
fix toArray()
fix returning documents
Added hash-, skip list, persistent indexes
harmonize filtering - filter on full filename.
mini modifications
standardize starting of servers for replication tests
Edge index compliant with design doc
another fix for #2404
Moved „removeLargeRange“ method to commons
Added length byte to IndexValue keys.
fixed issue #2404
Added drop to primary index
Added drop() to indexes
Fixes a coordinator crash in Clustered Traversal. In case of failover during query planning.
Fixed edge index
Expand on CORS documentation
Let ArangoDB handle the allow-credentials header
make the authentication tests run on directories
...