Motivation / Problem

Changing the liveries setting "Show vehicle-type specific liveries" does not have an immediately visible effect.
The colour map for individual vehicles is cached, but changing the setting does not invalidate the cache.

Description

This patch resolves this by calling the existing function to locally invalidate all cached vehicle colour maps.

Limitations

Clearing cached colour maps should not have any other side effects. This information is not stored in save games.

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