* Cmdline parsing for `-pilot "<name>"`
Add cmdline parameter `-pilot` with required
argument name and export name as global var
`Cmdline_pilot`.
* Expose to scripting `isAutoselect`
Setting `-pilot` flag sets `ui.isAutoselect()` true
(as does `-benchmark_mode`).
* Skip pilot selection
and call `player_finish_select` with the given
player instead.
* More useful error message on pilot load error
Also display callsign
* Add pilot name as scripting variable
* Don't expose pilot flag to launchers
* make stored flag param `const`