Python dependency problems on modern ubuntu installs

[gazhay]

I was told to report this here as it is the appropriate place for 15.04 cura problems.

Cura cannot be installed on newish ubuntu systems due to a python dependency problem. Existing installs of cura which are on a system that is upgraded, to say ubuntu 16.04 will stop slicing, as the numpy install gets upgraded, and there are casting errors during slicing.

To solve the issue, at least on my cura,

In the file Cura/util/sliceEngine.py line 346

change from pos += (objMin + objMax) / 2.0 * 1000

to pos = numpy.add( pos, (objMin + objMax) / 2.0 * 1000, out=pos, casting='unsafe')

slicing them works.