Launchers: Cartridge Ammo + Trajectory and Reload Options

[ProfLander]

• Implement CWeaponRG6 and CWeaponMagazinedWGrenade cartridge ammo support for @ZoulKrystal
  • Now capable of loading and firing buckshot, slugs, and other non-explosive ammo
  • Also applies to M79 and other subclasses
• Implement CWeaponGrenadeLauncher to hold common GL code
• Factor CWeaponRG6 and CWeaponMagazinedWGrenade GL launch code into CWeaponGrenadeLauncher
• Parametrize launcher trajectory assist machinery
  • g_launcher_dynamic_range - Enable while unaimed
  • g_launcher_dynamic_range_zoom - Enable while aimed
  • g_launcher_dynamic_range_max - Maximum assist range
  • g_launcher_dynamic_range_mode - Target dynamic objects
• Implement g_fire_reloads_ubgl to control nonstandard UBGL reload behaviour
• Reinstate disabled auto-reload functionality, gated behind the g_auto_reload cvar

[themrdemonized]

I reverted this PR, reasons:

• RG-6 consumes twice of grenades, and presumably shoots 2 grenades as well
• M79 doesn't play shoot sound and animation
  Needs to be fixes