Motivation / Problem

Group autoreplace protection doesn't apply to sub-groups by default, but a hidden Ctrl feature exists for that.
Wagon removal may affect group only, or ungrouped vehicles, depending on context, and it's not very visible. There's also a hidden Ctrl feature when groups are concerned.

Description

Hints about Ctrl in tooltips where needed, and show when ungrouped or group are affected by "wagon removal" toggle.

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, gs_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker