Nametags - Visibility improvements

[mrschick]

When merged this pull request will:

• More reliable NT drawing on dismounted units while inside an open vehicle:
  It appears that the current LOD checks are too restrictive when mounted on vehicles like quads, preventing drawing of the tags of dismounted units. Needs some more testing.
• Make the setting GVAR(showCursorTagForVehicles) always show VC nametags:
  It appears that the setting didn't have any effect previously. Only setting nametags to "cursor only" would enable the functionality of displaying VC nametags from outside.
• More reliable NT drawing on a vehicle's commander from the outside:
  Would previously be blocked on some vehicles, again due to a too restrictive LOD check.
  Needs more testing, maybe it could become a List-type setting with options: Always/On cursor/On Keybind Toggle/Never.
• Show nametags of all units within an open vehicle to the outside:
  Could be setting-dependent, maybe a List with options: Always/On cursor/On Keybind Toggle/Never.

[BaerMitUmlaut]

Usually FIRE is the most accurate LOD.