Adds scarfs

These come in red and green, and can be equipped in the tie slot.
They are available from the ClothesMate vendomat. Sprites by Nienhaus.
9 more scarves and small corgi cleanup

Adds 9 more scarves (light blue, dark blue, orange, yellow, purple,
white, black, zebra and christmas).
Cleaned up corgi code a little bit, specially the parts involving icon
updates. Fixes a bug where adding a hat to a dead corgi didn't make you
drop your hat and created duplicate items. Makes corgis only use one
head/back mob sprite and rotate it appropriately. Call
regenerate_icons() only when needed now, instead of doing so every tick
on Life().
Merge branch 'master' into scarfs

Conflicts:
	icons/obj/clothing/ties.dmi
Adds 3 more scarves

These striped scarves are made by MrSnapwalk. They are included in the
ClothesMate along with the other scarves (sprited by Nienhaus). These
have a striped texture.
Merge pull request #6446 from tkdrg/scarfs

Adds scarves