issue #67: refactored and added support for 0=×/⍴⍵

* removed extra whitespace
* simplified "{r=⍴⍵:⍵ ⋄ (-r)↑ones,⍵}" to "{(⍴⍵)↓ones,⍵}" and then to "(⍴ ↓ ones∘,)"
* inlined "ones"
* "max" was used to refer to two different things, renamed the first to "r"
* added support for the case "0=×/⍴⍵" and tests