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