HSEARCH-1455 Cleaning up message logger interface. Removing unused methods and added @SuppressWarnings for deprecations
HSEARCH-1455 Updating docs

- Removing mention of @Similarity
- Removing mention of compound index option
- Fixing broken table formatting
HSEARCH-1455 Removing deprecation on ContextHelper, since this class is not replaceable for now
HSEARCH-1455 Adding @Deprecation annotation
HSEARCH-1602 Switching header in Java and XML files. Configuring Checkstyle to check java and xml resource files against these headers
HSEARCH-1312 Adding test to show that reported errors are unrelated.

- Improving error messages and use consistently the Log interface.
- Simplifying NullEncodingFieldBridge creation