added traffo.c from openptv-python/src
created trafo.h for the consistency
modified functions to use the modern call type (explicit argument types)
added check_trafo (empty so far)
added check_trafo to CMakeLists.txt
added check_trafo.c tests of all four functions in traffic
adopted Alessandro format for pixel_to_metric and metric_to_pixel with wrapping
updated check_trafo.c to work with the new argument order (output is always first)
WARNING - a lot of signatures will have to change across the code
RECOMMENDED - use the wrapped version that sends control_par *cpar instead of the components imx,imy…
added metric_to_pixel_control_par and pixel_to_metric_control_par
added respective tests
changed the names according to Yosef comment:
new functions are using previous simple names: metric_to_pixel and pixel_to_metric
old versions are called old_metric_to_pixel and old_pixel_to_metric
these two functions removed from the header file trafo.h (not exported), used locally in traffo.c (creates warning in the test)
tests are updated
Merge pull request #32 from alexlib/trafo

trafo.{c,h} pull request