Adds labels to logistics chests so they can be distinguished without colour.

Adds new entities with labels so their purpose is clear when using Factory Search and similar mods. This is useful for mods that have byproducts if not using a train routing mod that has priorities.

Suggested use:

Provider stations use the red frames with the triangle on the left. Requester stations use the blue frames with the triangle on the right.

Routes are between providers and requesters with the same priority. Numbers are assigned by provider priority.

0 Automatic. Always safe to use. The export block merges material from different priorities before exporting it.
1 Void. Use this first, or just give up and void it.
3 Byproduct. Use this fast so the line doesn't jam.
5 Unspecified. This chart uses all the odd numbers.
7 Storage.
9 Direct production. Use this last.

Many things (at least on 1x) can be handled with transfer blocks; bring in material from all priorities, use a gazillion priority splitters, then export it as Automatic.

For higher volumes, I'm very inconsistent. Some material created as byproducts go to the storage block, and blocks that need that material draw from there. Some consumption blocks bring in both byproduct and direct material, then prioritize on receipt. Some direct production blocks bring in byproduct, merge it with direct production, then export as Automatic. Some byproduct production blocks bring in direct, then merge and export as Automatic. It all depends on relative volumes and how much room is in each block. Note that carrying material to a transfer or storage area, rather than directly to the consumer, is often easier, but also creates extra traffic.

Ideas for Future
- Setting so can show letters instead of numbers. A would show instead of 0, V instead of 1, etc. Numbers were done first since they're probably less confusing.
- Localizations, to avoid Unknown Key messages.
- Better resolution graphics: 64 instead of 32.