Add style for expressions

[jaxxzer]

Patrick likes no spaces for * or / operators, and space for everything else:
if ((_maxDepthToDraw - _minDepthToDraw)*_minPixelsPerMeter < 200) {

I like single space between every mathematical or logical operator:
if ((_maxDepthToDraw - _minDepthToDraw) * _minPixelsPerMeter < 200) {

Is this something we should add a guideline for? or just leave it to preference?

There is also the matter of a space after the if or while statements.

[jaxxzer]

@patrickelectric and @Williangalvani point out these resources which are in favor of patrick's preference
https://www.python.org/dev/peps/pep-0008/#other-recommendations
https://github.com/opencv/opencv/blob/master/modules/core/include/opencv2/core/mat.hpp#L106
https://github.com/eigenteam/eigen-git-mirror/blob/master/Eigen/src/Jacobi/Jacobi.h#L200