* issue 496.3: move more coordinator-related logic out of TRI_vocbase_t, rename some arangosearch view configuration parameters, remove some consolidation policies, update iresearch to revision 6fd9760d81b136f769e277ea5b8f53996ed7a1ca
* address potential deadlock between link creation and FlushThread
* remove code causing nullptr access
* add back lock around reader reopen
* revert: address potential deadlock between link creation and FlushThread
* invalidate payload for each field in FieldIterator before setting a value
* update iresearch to codebase as of 20181011
* backport: address cluster test failures
* backport: address dump test failures
* backport: address discrepency in view creation between single-server and cluster
* backport: address test failure on cluster (revert change)
* backport: address test failures
* backport: address MSVC build issues
* backport: address issue with LogicalDatasource destructing after TRI_vocbase_t
* Revert "backport: address issue with LogicalDatasource destructing after TRI_vocbase_t"
This reverts commit 4f9880bbaa22194dfbb604b5a54658de1d447ac1.
* issue 450.3: use a single configuration policy differentiated by 'type' with arbitrary number of configurable parameters
* ensure test data is persisted to the test directory
* add missed declaration
* fix typo
* add full namespace and includes
* issue 400.2.4: register IResearchView sync tasks with IResearchFeature, remove unused configuration parameter
* set flag before notify, fix failures in new tests from 'devel'
* revert set flag before notify, fix more failures in new tests from 'devel'
* fix even more failures in new tests from 'devel', backport: do not reset notification flag if pending tasks were seen
* fix still more failures in new tests from 'devel'
* try to work around buggy test failures
* issue 401.2: split IResearchViewMeta into the user configurable part and internal state
* backport: update documentation and integration tests to reflect the IResearchViewMeta changes
* backport: addresss typo
* backport: address another typo