* 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 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