[DOCS] Updated ICU-Plugin docs from the repo README
[DOCS] Removed enable_position_increments in stop filter
[DOCS] Fixed typo
[DOCS] Changed capitalization of operator in rescore query
Warn users with IAE if pos_inc is disabled in 'stop' filter
fix typo - s/Deprected/Deprecated
Add simple test for delete by field query
Disable ConcurrentDynamicTemplateTests for now
Changed documentation to use getter notation

Updated some java documentation to reflect the use of getters instead of calling methods based on field names.

Relates to #2657
use the already used constant for match no filter
Better logic ignoring filters when parsing
When parsing a filter, we effectively have a case where we need to ignore a filter. For example, when an "and" filter has no elements. Ignoring a filter is different compared to matching on all or matching on none, because an and filter with no elements should simply be ignored in the context of a bool filter for example, regardless if its used within a must or a must_not filter.

We should be consistent in our codebase when handling these use case. See also #3809

closes #3838
[DOCS] Added pages explaining lucene query parser syntax and regular expression syntax
Rejecting invalid fields inside of completion field

Only valid fields (input, output, weight and payload) are now allowed inside a completion field.
This makes sure that typos like "inputs" are caught on indexing.
Improve exception handling for river startup

Due to a change in 0.90 some exceptions may show up when starting a river,
even though this is not a problem as the shard has not been initialized
yet and a retry is scheduled.
Remove @Required annotation

The @Required annotation is used for documentation purposes only anyway.
Add FieldMappers before adding Mappers (used for parsing) and while holding the relevant's ObjectMapper mutex

Adding the mappers first could cause the wrong FieldMappers to be used during object parsing

Also:
Removed MergeContext.newFieldMappers, MergeContext.newObjectMappers and relatives as they are not used anymore.
Similarly removed MergeContext.addFieldDataChange & fieldMapperChanges as they were not used.

Closes #3844
Update Lucene to version 4.5.0.
plugin -remove deletes bin directory
I tried to install a plugin directly from disk, but used the wrong arguments. Totally my fault for not RTFM properly.

However, by following the instructions printed out by `bin/plugin`, I ended up deleting my $ES/bin directory.

```
$ pwd
/tmp/elasticsearch-0.90.5
$ ls
LICENSE.txt    NOTICE.txt     README.textile bin            config         lib
$ bin/plugin --install file:///tmp/foo.zip
-> Installing file:///tmp/foo.zip...
Failed to install file:///tmp/foo.zip, reason: plugin directory /tmp/elasticsearch-0.90.5/plugins already exists. To update the plugin, uninstall it first using -remove file:///tmp/foo.zip command
$ bin/plugin -remove file:///tmp/foo.zip
-> Removing file:///tmp/foo.zip
Removed file:///tmp/foo.zip
$ ls
LICENSE.txt    NOTICE.txt     README.textile config         lib
```

I reproduced the problem in 0.90.5 and the latest master.
Closes #3847.
Added third highlighter type based on lucene postings highlighter

Requires field index_options set to "offsets" in order to store positions and offsets in the postings list.
Considerably faster than the plain highlighter since it doesn't require to reanalyze the text to be highlighted: the larger the documents the better the performance gain should be.
Requires less disk space than term_vectors, needed for the fast_vector_highlighter.
Breaks the text into sentences and highlights them. Uses a BreakIterator to find sentences in the text. Plays really well with natural text, not quite the same if the text contains html markup for instance.
Treats the document as the whole corpus, and scores individual sentences as if they were documents in this corpus, using the BM25 algorithm.

Uses forked version of lucene postings highlighter to support:
- per value discrete highlighting for fields that have multiple values, needed when number_of_fragments=0 since we want to return a snippet per value
- manually passing in query terms to avoid calling extract terms multiple times, since we use a different highlighter instance per doc/field, but the query is always the same

The lucene postings highlighter api is  quite different compared to the existing highlighters api, the main difference being that it allows to highlight multiple fields in multiple docs with a single call, ensuring sequential IO.
The way it is introduced in elasticsearch in this first round is a compromise trying not to change the current highlight api, which works per document, per field. The main disadvantage is that we lose the sequential IO, but we can always refactor the highlight api to work with multiple documents.

Supports pre_tag, post_tag, number_of_fragments (0 highlights the whole field), require_field_match, order by score and html encoding.

Closes #3704