feature: GUI size is not stored

[Phil]

1. Open Phatch
2. Resize the window
3. Close Phatch
4. Re-open Phatch

Actual behaviour:
Phatch opens but with its default window size, not its last size.

Expected behaviour:
Phatch ought to re-open with its last size (with a constraint that it can't be less than some min width & height)

This feature ought to be available for the other Phatch windows, namely the action window, execution window, report window.

IMPLEMENTATION:
* on close store in a file "windows_sizes": window-id; window-width ; window-height
* on first open set the window width & size according to the file read "windows_sizes"

Thanks