Docs: fix documentation for bloom filter defaults
The `nested` aggregator should also resolve and use the parentFilter of the closest `reverse_nested` aggregator.

Closes #6994
Closes #7048
Aggregations: fixed value count so it can be used in terms order

Closes #7050
[TEST] Ignore Lucene40 codec
Docs: Add Drupal Search API Elasticsearch module

The module at drupal.org/project/elasticsearch has been abandoned. The Search API Elasticsearch module allows Drupal to use Elasticsearch as a backend for Search API.

Closes #7001
[TEST] All shards should be allocated before snapshotting.
Update request-body.asciidoc

Added link from `timeout` to time-units

Closes #6361
Add HierarchyCircuitBreakerService

Adds a breaker for request BigArrays, which are used for parent/child
queries as well as some aggregations. Certain operations like Netty HTTP
responses and transport responses increment the breaker, but will not
trip.

This also changes the output of the nodes' stats endpoint to show the
parent breaker as well as the fielddata and request breakers.

There are a number of new settings for breakers now:

`indices.breaker.total.limit`: starting limit for all memory-use breaker,
defaults to 70%

`indices.breaker.fielddata.limit`: starting limit for fielddata breaker,
defaults to 60%
`indices.breaker.fielddata.overhead`: overhead for fielddata breaker
estimations, defaults to 1.03

(the fielddata breaker settings also use the backwards-compatible
setting `indices.fielddata.breaker.limit` and
`indices.fielddata.breaker.overhead`)

`indices.breaker.request.limit`: starting limit for request breaker,
defaults to 40%
`indices.breaker.request.overhead`: request breaker estimation overhead,
defaults to 1.0

The breaker service infrastructure is now generic and opens the path to
adding additional circuit breakers in the future.

Fixes #6129

Conflicts:
	src/main/java/org/elasticsearch/index/fielddata/IndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/IndexFieldDataService.java
	src/main/java/org/elasticsearch/index/fielddata/RamAccountingTermsEnum.java
	src/main/java/org/elasticsearch/index/fielddata/ordinals/GlobalOrdinalsBuilder.java
	src/main/java/org/elasticsearch/index/fielddata/ordinals/InternalGlobalOrdinalsBuilder.java
	src/main/java/org/elasticsearch/index/fielddata/plain/AbstractIndexOrdinalsFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/DisabledIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/IndexIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/NonEstimatingEstimator.java
	src/main/java/org/elasticsearch/index/fielddata/plain/PackedArrayIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/ParentChildIndexFieldData.java
	src/main/java/org/elasticsearch/index/fielddata/plain/SortedSetDVOrdinalsIndexFieldData.java
	src/main/java/org/elasticsearch/node/internal/InternalNode.java
	src/test/java/org/elasticsearch/index/aliases/IndexAliasesServiceTests.java
	src/test/java/org/elasticsearch/index/codec/CodecTests.java
	src/test/java/org/elasticsearch/index/fielddata/AbstractFieldDataTests.java
	src/test/java/org/elasticsearch/index/fielddata/IndexFieldDataServiceTests.java
	src/test/java/org/elasticsearch/index/mapper/MapperTestUtils.java
	src/test/java/org/elasticsearch/index/query/IndexQueryParserFilterCachingTests.java
	src/test/java/org/elasticsearch/index/query/SimpleIndexQueryParserTests.java
	src/test/java/org/elasticsearch/index/query/guice/IndexQueryParserModuleTests.java
	src/test/java/org/elasticsearch/index/search/FieldDataTermsFilterTests.java
	src/test/java/org/elasticsearch/index/search/child/ChildrenConstantScoreQueryTests.java
	src/test/java/org/elasticsearch/index/similarity/SimilarityTests.java
Change logging level for circuit breaking to warn
[CORE] Support parsing lucene minor version strings

We parse the version that is shipped with the Lucene segments in order
to find the version of lucene that wrote a particular segment. Yet, some lucene
version ie:
 * 4.3.1 (Elasticsearch 0.90.2)
 * 4.5.1 (Elasticsearch 0.90.7)
 * 3.6.1 (pre Elasticsearch 0.90.0)

wrote illegal strings containing the minor version which causes IAE exceptions
being thrown from lucenes parsing method.

Closes #7055
[CORE] Support alpha/beta releases in version parsing too

Pull Request #7055 fixed Version parsing for bugfix releases
causing problems with minor version in segments files. Even though
we never release anything with lucene in alpha / beta status this
commit fixes lenient parsing for these cases.

Relates to #7055
add missing import
[QUERY] Separate parsing impl from setter in SearchParseElement

This commit makes it easier to reuse the inner highlighting, fetch
and rescore parsing logic by plugins or other internal parts.

Closes #3602
Aggregations: Stops direct subclassing of InternalNumericMetricsAggregation

Must subclass either InternalNumericMetricsAggregation.SingleValue or InternalNumericMetricsAggregation.MultiValue
Docs: Add links to the equivalent aggs in facets documentation.
Updated es_release_notes script to replace backticks with code tags
Plugin Lucene version checker: use `Lucene.parseVersionLenient`

With commit 07c632a2d4dbefe44e8f25dc4ded6cf143d60e41, we now have a new Lucene.parseVersionLenient(String, Version) method which tries to find an existing Lucene version based on the two first digits X.Y of X.Y.Z String.
Internal: use AtomicInteger instead of volatile int for the current action filter position

Also improved filter chain tests to not rely on execution time, and made filter chain tests look more similar to what happens in reality by removing multiple threads creation in testTooManyContinueProcessing (something we don't support anyway, makes little sense to test it).

Closes #7021
Rest: fixed filters execution order to be from lowest to highest rather than the other way around

Closes #7019
[TESTS] fix circuit breaker tests for remote clusters and bwc

Adds additional version checks in NodeStats for older versions

When using an external cluster (backwards compatibility tests), the act
of checking the request breaker requires a network buffer, which
increments the breaker. This change only checks the request breaker in
InternalTestCluster and uses Guice to retrieve it instead of
a (possible) network request.

Also removed the now unused InternalCircuitBreakerService class