Implements #710. Adding new unit tests.
Conflicts:
	.gitignore
	src/main/java/com/jaeksoft/searchlib/Client.java
	src/main/java/com/jaeksoft/searchlib/index/IndexSingle.java
	src/main/java/com/jaeksoft/searchlib/index/WriterInterface.java
	src/main/java/com/jaeksoft/searchlib/index/WriterLucene.java
	src/main/java/com/jaeksoft/searchlib/result/ResultDocuments.java
Merge remote-tracking branch 'upstream/master'
Merge pull request #723 from emmanuel-keller/master

Implements #710