File crawler bugs and improvement
Conflicts:
	src/main/java/com/jaeksoft/searchlib/filter/FilterCacheKey.java
	src/main/java/com/jaeksoft/searchlib/filter/FilterListCacheKey.java
	src/main/java/com/jaeksoft/searchlib/index/DocSetHitCacheKey.java
	src/main/java/com/jaeksoft/searchlib/sort/SortField.java