Quiver3d fixes

* numpy 1.6 does not support 3+ arguments for meshgrid
* actually use the sanitized data (fixes broadcasting issue)
* use argi through-out the function
* don't fail on zero flow, just don't draw a quiver
it isn't being dropped per se. What seemed to have happened is a bad merge, or something. This was in the original PR, but we needed to greatly rework it do broadcasting and other sanity checks which comes before this. This code that was removed is completely unnescessary because at this point, everything has been made into numpy arrays and have been flattened() (or compressed() if masked).