experimental MapStream
type inference ftx
added mergeKeys method
.
javadoc mapstream
statif factory for pair varargs @MapStream.of
Merge branch 'master' of https://github.com/alexcrt/JavaBoost into mapstream

Conflicts:
	src/main/java/org/javaboost/pair/Pair.java
Merge pull request #16 from alexcrt/mapstream

Mapstream