* Applied review cAdded sceleton optimizer functionomments
* Added mask for rule
* Applied review cAdded sceleton optimizer functionomments
* Added mask for rule
* adding plan traversal for rule
* Rule execution block developing
* Experiment with additional block
* LIMIT node modifications
* implemented late materialization base version.
* Code cleanup
* Added check for variable usage
* Implemented serialization and cloning
* Fixed build errors
* Implemented late materialization for LimitNode
* Moved materialization to Sort Node
* Removed LimitNode modiications
* Implemented skipRows to speedup single server
* Added tests for optimizer rule
* fixed build
* Fix mac build
* Fixed mac build
* Fixed PR test run errors
* Added tmp fix for cluster test runs
* removed debug print
* Make materialization stick to last sort node. Add late materialization to explainer
* Updated optimization rule to search optimal SortNode to do materialization
* Refined optimization rules for cluster
* Added tests for SortExecutor and IResearchViewNode
* Fixed mac buid. Removed misplaced assertion.
* Fixed build
* Updated tests. Coded cleanup
* Code cleanup
* made function name for SortedExecutor match name in ConstraintSortedExecutor
* cleanup
* Fixed test run
* made scoring results stable across cluster
* Make optimize rule stop if sort node for limit node is not suitable
* Disabled constrained sort for materializing SortNode
* reverted SortNode modifications
* Implemented separate materializer node
* Fixed tests to account new materialize node
* Code cleanup
* reverted debugging change
* Fixed test jslint error and comments
* MaterializeNode renamed
* enum value renamed for materialize node
* Code cleanup
* code cleanup and optimization
* Fixed clang warning
* Applied review comments
* Out variable planning moved to materialize node
* inlined getters in ReadContex
* move IResearchViewSort into separate unit
* ensure sort is propagated to IResearchLink
* update iresearch and extend some tests
* implement insertion of sorted values, store value comparator in link
* add tests for VPackComparer
* minor cleanup
* fix issue with sort definiton propagation
* propagate error message from index factory
* add integration tests for sorted indexes, single server
* initial implementation of IResearchViewMergeExecutor
* move iresearch::VPackComparer to separate translation unit
* store collection in IndexReadBuffer for IResearchViewMergeExecutor
* set primary sort from optimizer rule
* add some tests for sorted view case
* extend IResearchViewNode tests
* simplify primary sort definition
* pretty print order condition covered by arangosearch in query explanation
* fix compilation with g++-8
* address catch test failures
* fix tests
* adjust arangosearch optimizer rule to optimize sort in case of cluster
* make tests for sorted indexes work in cluster too
* fix tests
* extend js tests for sorted indices
* fix keyword in query explainer
* ensure sort-limit rule works with views
* backport ngram analyzer fix from upstream
* address jslint errors
* modify IResearchViewSort to support boolean direction specification format
* add some tests
* add tests
* add skip functionality
* extend tests
* add more catch tests
* inline some methods
* address jslint errors
* extend catch tests to reproduce the failure
* add some tests for check fullcount
* add more tests
* extend tests
* temporarily comment out broken tests
* extend js tests
* address review comments
* address jslint errors
* update iresearch
* added SEARCH keyword
* fixes jslint errors
* add incompatibility notice
* remove VIEW keyword (does not work yet!!)
* add initial support for SEARCH keyword to optimizer rules
* replace FILTER with SEARCH keyword in tests
* removed VIEW keyword, make shell_server_aql tests pass again in single server
* cleanup
* handle SEARCH clause for views
* make SEARCH a non-keyword
* fixed an issue with duplicate variables
* fixed 3 tests
* fix SEARCH statement support for views
* minor refactoring
* fix integration tests
* optimize SEARCH conditions a bit more
* fix jslint error
* fixed wrong comments and typo in class name
* fix documentation
* adjust recovery tests to use SEARCH instead of FILTER
* fix another failing test