[ptx] new command line tool for vignetting, radial distortion and TCA correction

[Pablo d'Angelo]

Hi,

I have written a command line tool, whose working title is fulla, to perform
vignetting, radial distortion and transversal chromatic abberation correction.

In principle, it is the vignetting correction algorithm as in hugin/nona,
and radial distortion correction for each channel.

Contrary to the correct filter, the green channel radial distortion is used
as base for the blue channel and red channel radial distortion correction.

This enables people to use the PTLens distortion coefficients and add TCA
correction parameters (which can be determined using hugin or some other
software like PTshift or Picture Window Pro), without having to combine the
radial distortion parameter and the TCA distortion parameters by hand.

ciao
  Pablo