Don't rotate the entire plate, fix the calculations

[ivoflipse]

Currently when encountering a measurement where the dog walked right to left, instead of left to right, I rotate the entire plate. While this 'solves' most of my problems, I'd prefer to leave the data untampered and show it as is.

However, this has some consequences, as currently paws would be displayed upside down and making an average of that would be a disaster. So add a variable to each Contact object, indicating its orientation. This can then be used where necessary.

[ivoflipse]

In the latest version, I'm storing the data as is, while storing a boolean value whether or not the plate is 'rotated'. That information should be used to convert the results when trying to average with measurements that go in another direction.

For example, the COP would go in opposite directions, so that would have to be inverted in order to average. Other calculations, such as step length/width probably should be made direction agnostic, so just calculate the distance relative to the other paw.

[ivoflipse]

While the original data (both measurement and plate) are stored as is, I'll change it such that when I look the data, it will 'correct' it. Else I'll have to keep rotating the contacts every time I want to calculate an average for example