added a function evaluation_from_estimated_F in the pointing_accuracy
module. It computes the pointing error by looking at the highest
distance between a keypoint and the epipolar line of its match. The
epipolar line is given by an estimated fundamental matrix, estimated
from the rpc data.
fixed path problem
added c utils from Enric's imscript, for bilinear interpolation
increased epipolar_tresh from .1 to .5 pix, and lowered sift thresh from
.6 to .4 to remove more false matches.
added the option of computing the rectifying homographies from sift
matches directly, without using calibration (ie rpc) data
bilinear interpolation of height maps, to transfer them on the original
grid