* Make the app progress indicator only have the indeterminate state
when the taskbar indicator is used (causes an uused variable warning
on wx<3.1)
* Remove unused dry run variable in pcb_netlist.h
* Remove unused forceDropAnnotations from the paste special dialog
since the dialog only controls keeping them.
ADDED: Progress indicator in the taskbar
This adds a progress indicator to the Windows and macOS taskbar
icons to display the progress of some operations.
Note, this requires wxWidgets 3.1+