Only show max 50 aircraft by default and provide a "Show More"
button. This prevents locking the GUI for up to nearly 15 seconds
with showing the list of all aircraft.
- Increase default size.
- Run parse_markdown on description to remove multi
whitespace, possible present in catalog.xml and
also support simple, one-level bullet point lists.
- Needs FlightGear compiled with -DENABLE_PACKAGE_SYSTEM.
- Shows only first 100 available aircrafts.
- Now progress indication on install/remove (need to reopen
dialog afterwards)