basic implementation for scalar objects having "nil" shape
Merge branch 'nil-scalar-shape' into develop

Conflicts:
	src/main/clojure/clojure/core/matrix.clj
extra docstrings
swap default implementation back to persistent vector
Switch off AOT
improve equality testing
better shape testing with PSameShape protocol
use same-shape? for faster equality tests
more use of same-shape?
improve same-shape? for high arity case
tidy code and docstrings
eliminate duplicate pprint code
tidy, move normalise-proabilities out to core.matrix.stats library