fixed broken references in client docs
increased crash version

Conflicts:
	CHANGES.txt
prepare release 0.38.2

Conflicts:
	CHANGES.txt
	core/src/main/java/io/crate/Version.java
Merge pull request #818 from crate/h/forwardport-0382

forwardport 0.38.2
fix hidden directive in docs
add arithmetic functions
fixup! add arithmetic functions