Fail geohash_cell filter if geohash prefix is not enabled
closes #4335
Override DefaultExceptionHandler to filter out certain exceptions

We have the situation that some tests fail since they don't handle
EsRejectedExecutionException which gets thrown when a node shuts
down. That is ok to ignore this exception and not fail.
We also suffer from OOMs that can't create native threads but don't
get threaddumps for those failures. This patch prints the thread
stacks once we catch a OOM which can' create native threads.
Fixed incorrect results with `has_child` query with score mode if the parent type has nested object types. The inner objects (Separate Lucene docs) are also emitted as hits, which incorrectly decreased the count down short circuit mechanism in the `has_child` query.

Closes #4341
better error handling when processing refresh/update mapping
don't fail the whole bulk of updates, just the specific ones, and warn log it
Allow to disable sending a refresh-mapping to master node
When a node processed an index request, which caused it to update its own mapping, then it sends that mapping to the master. While the master process it, that node receives a state that includes an older version of the mapping. Now, there is a conflict, its not bad (i.e. the cluster state will eventually have the correct mapping), but we send for a refresh just in case form that node to the master.

With a system that has extreme cases of updates and frequent mapping changes, it might make sense to disable this feature. The indices.cluster.send_refresh_mapping setting can be introduced to support that (note, this setting need to be set on the data nodes)

Note, sending refresh mapping is more important when the reverse happens, and for some reason, the mapping in the master is ahead, or in conflict, with the actual parsing of it in the actual node the index exists on. In this case, the refresh mapping will result in warning being logged on the master node.

closes #4342
test fix
test fix
[DOCS] Completion suggest: Clarify de-duplication, optimize/merge

This contribution is based on the feedback given in issue #4254 and
issue #4255, and should clear things up, when suggestions are being
removed and not displayed anymore after deletion of data.
Added a FsStats.total section that sums up all stats for the different path.dirs. Added `disk_io_size` and `disk_io_op` to the toXContent output, summing up `disk_read_size+disk_write_size` and `disk_writes+disk_reads` respectively.

Closes #4344 , Closes #4343
remove help command, list all cat commands in /_cat?h endpoint
Cat: Add nodes column descriptions.
Cat: Add descs for rest of actions.
Fix _all boosting.

_all boosting used to rely on the fact that the TokenStream doesn't eagerly
consume the input java.io.Reader. This fixes the issue by using binary search
in order to find the right boost given a token's start offset.

Close #4315
[DOCS] Fix outdated link to wonderdog in community integration
[Docs] Document which encoding should be used in order to make sense of the offsets returned by the term vectors API.

Close #4363
Apply slop correctly if phrase query is wrapped in a filtered query.

If a phrase query is wrapped in a filtered query due to type filtering
slop was not applied correctly. Also if the default field required a
type filter the filter was not applied.

Closes #4356
Optimize dynamic mapping updates on master by processing latest one per index/node
Instead of processing all the bulk of update mappings we have per index/node, we can only update the last ordered one out of those (cause they are incremented on the node/index level). This will improve the processing time of an index that have large updates of mappings.
closes #4373
update the test to use the same API as 0.90
so backports will be simpler for now
Fixed local option explanation in TESTING readme
Add an `usage` key to the CPU section of OsStats.toXContent.

 This is just the sum of existing `sys` and `user`

Closes #4374