#4 Switching camera presets will force complete chunk reloads

[CJ Kucera]

When using home/end/ins/del to change between camera presets, X-Ray will currently invalidate its entire chunk cache and re-load those areas; this includes wiping and redrawing the minimap as well. Sometimes this might be the correct thing to do, but often we already have those areas cached and drawn to the minimap, so it'd be nice to reuse that data if possible.