Update courtyard dimensions in fpw file if these can be determined.

[Bert Timmerman]

Make calculations of the courtyard dimensions based on the offset w.r.t. the package dimensions when these dimensions are available.

Update the courtyard dimensions in the global variables and GUI, before writing values to the footprintwizard file.

Choices how to solve this can be:

1) only write values which are explicit ("hard") values given by the user (these are to be considered "correct" values).

2) do some math and write implicit ("soft") values to the footprintwizard file.