swift 3 builds and fixed some nsnumber values for correct default slider values

[mredig]

Most of the edits were actually pulled from another fork I picked at random that fixed the swift 3 build issues.

However, I noticed that a lot of filters has horrible slider ranges and default values (I believe as a result of the swift 3 conversion), so I found the issue and cast the filter values as NSNumbers and then used the "floatValue" of an NSNumber to get those min, max, and default values, instead of casting NSNumbers as Float.