[Cin] frei0r plugins

[Andrea paz]

Personally I find the following plugins interesting:

- Alpha operations (frei0r.alpha0ps): Display and manipulation of the
alpha channel
- Alpha shapes (frei0r.alphaspot): Draws simple shapes into the alpha channel
- Color Distance (frei0r.colordistance): Calculates the distance
between the selected color and the current pixel and uses that value
as new pixel value
- Defish (frei0r.defish0r): Non rectilinear lens mappings
- Face detect (frei0r.facedetect): Detect faces and draw shapes on
them using OpenCV
- Lens Correction (frei0r.lenscorrection): Allows compensation of lens
distortion
- Luminance (frei0r.luminance): Creates a luminance map of the image
- Rectangular Alpha mask (frei0r.mask0mate): Creates an square
alpha-channel mask
- Medians (frei0r.medians): Implements several median-type filters
- Primaries (frei0r.primaries): Reduce image to primary colors
- Color Selection (frei0r.select0r): Color based alpha selection
- Tint (frei0r.tint0r): Maps source image luminance between two colors specified