TST: NormExpan sandbox.distributions: add basic unittests
BUG: NormExpan sandbox.distributions, no shape parameter see #1397
REF/DOC: sandbox.distribution.extras move examples to script file
DOC/REF: make example script runnable (fix imports)
Merge pull request #1403 from josef-pkt/BUG_NormExpan

BUG Bug norm expan shapes closes #1397