Internal: harden recovery for old segments

When a lucene 4.8+ file is transferred, Store returns a VerifyingIndexOutput
that verifies both the CRC32 integrity and the length of the file.

However, for older files, problems can make it to the lucene level. This is not great
since older lucene files aren't especially strong as far as detecting issues here.

For example, if a network transfer is closed on the remote side, we might write a
truncated file... which old lucene formats may or may not detect.

The idea here is to verify old files with their legacy Adler32 checksum, plus expected
length. If they don't have an Adler32 (segments_N, jurassic elasticsearch?, its optional
as far as the protocol goes), then at least check the length.

We could improve it for segments_N, its had an embedded CRC32 forever in lucene, but this
gets trickier. Long term, we should also try to also improve tests around here, especially
backwards compat testing, we should test that detected corruptions are handled properly.

Closes #8399

Conflicts:
	src/main/java/org/elasticsearch/index/store/Store.java
	src/test/java/org/elasticsearch/index/store/StoreTest.java
more debug logging
Docs: Fix some typos, and sentence structure.

Closes #8404
[STORE] Calculate Alder32 Checksums for legacy files in Store#checkIntegrity

Previously we didn't calculate this checksums even though we have a checksum
to compare. Since we now also verify checksums for legacy files #checkIntegrity
should also calculate the legacy checksums.

Closes #8407
[STORE] Synchronize operations that modify file mappings on DistributorDirectory

The rename(String, String) method doesn't allow this implementation to use a simple
concurrent map. There is a race during a rename operation where files are not fully
renamed but already visible via #listAll(). This inconsistency can lead to problems
when opening commit points since the pending_segments_N as well as segments_N are visible
but not yet atomically renamed.

Yet, non of the methods that are synced are long running such that adding sychronization
doesn't introduce bottlenecks here. The Direcotry#sync(...) method is not synchronized since
it doesn't change any mapping nor does it depend on the mapping.
[PING] Don't bubble up exception if we are shutting down and ping schedules get rejected
Core: Remove NestedDocsFilter, because it isn't used and also don't eagerly load it in bitset filter cache.

Closes #8414
Test: MinimumMasterNodesTests.testCanNotBringClusterDown should always set minimum master nodes.
Internal: Inverse DocIdSets' heuristic to find out fast DocIdSets.

DocIdSets.isFast(DocIdSet) has two issues:
 - it works on the DocIdSet interface while some doc sets can generate either
   slow or fast sets depending on their options (eg. whether an OrDocIdSet is
   fast or not depends on the wrapped clauses).
 - it only works because the result of this method is only taken into account
   when a DocIdSet has non-null `bits()`.

This commit changes this method to work on top of a DocIdSetIterator and to use
a black-list rather than a white list: slow iterators should really be the
exception rather than the rule.

Close #8380
[TEST] added Get Index bwc test
[docs] add 2d vis for decay functions and parameters

closes #8420
Docs: Removed old coming/added tags
Scripting: Add score() back to AbstractSearchScript

See #8377
closes #8416
closes #8417
Rest API: indices.delete should have "index" as a required param
Core: add max_determinized_states to query_string and regexp query/filter

This prevents too-difficult regular expressions from consuming
excessive RAM/CPU; the default max_determinized_states is 10,000 (same
as Lucene) but query_string and regepx query/filter can override
per-request.

The also upgrades to a new Lucene 5.0.0 snapshot.

Closes #8386

Closes #8357
remove wrong repository
Internal: extend refresh-mapping logic to the _default_ type

When data nodes receive mapping updates from the master, the parse it and merge it into their own in memory representation (if there). If this results in different bytes then the master sent, the nodes will send a refresh-mapping command to indicate to the master that it's byte level storage of the mapping should be refreshed via the document mappers. This comes handy when the mapping format has changed, in a backwards compatible manner, and we want to make sure we can still rely on the bytes to identify changes.  An example of such a change can be seen at #4760.

This commit extends the logic to include the `_default_` type, which was never refreshed before. In some unlucky scenarios, this caused the _default_ mapping to be parsed with every cluster state update.

Closes #8413
Test: switch to TRACE logging for some components
Test: restore logging to prior state
Query: add option for analyze wildcard/prefix also to simple_query_string query

The query_string query has an option for analyzing wildcard/prefix (#787) by a best effort approach.

This adds `analyze_wildcard` option also to simple_query_string.

The default is set to `false` so the existing behavior of simple_query_string is unchanged.