Add -import to command line to add additional testing capability

[KeyWorksRW]

Description:

Currently we test importing by comparing a the appearance of a form in the original designer (e/g. wxFormBuilder) side by side with the appearance of the form in wxUiEditor. We could take that one step further by adding an -import command line switch, which coupled with -generate would make it possible to regenerate the code and see if the resulting program runs and looks the same as the original. That would be particularly useful for importing from designers that don't necessarily display their UI correctly (e.g., wxFormBuilder's display of wxRadioBox is currently broken). By using the command line, we ensure that no additional modifications are made that are not available in the original designer (e.g., setting focus, adding hidden text, etc.).