Add the ability to choose the interpolation mode used when resizing an image

[jSdCool]

added the ability to choose witch interpolation mode to use when resizing an image.

to do this there is a new overload for PImage.resize() that takes 3 ints (width, height, interpolation mode) there are also 3 new PConstants for the mode they are: NEAREST_NEIGHBOR, BILINEAR, and BICUBIC. They have a value of 0 1 and 2 respectively.