Removed Iminv.pro from tracking in repo an added a .gitignore file

This is a configuration file for each PC. Shouldn't really be in this
repo. The .gitignore should stop us commiting our configurations by mistake.
Got colourMap() working

Problem with the calculation giving numbers greater than 255, this was
being modulo(255) by the qRgb function to produce numbers that were too
small.

Put in a couple of if statements to catch the max value. Seems to
produce a colourmap that is same as before