Added Bilateral Smoothing filter

This filter is an advanced blurring technique which reduces noise as well as preserving sharp edges. It also has artistic effect applications.

@tannerhelland:  If you wish to reduce the number of controls in the dialog, you can remove the power parameters and make them optional. I recommend the default values of 2. Also, I don't recommend running this filter in the IDE, as it's extremely slow due to the processing requirements.