New MC 1.8/1.7.6 skin support (64x64)

There are some enhancements planned for MC 1.7.6 (and/or 1.8?) adding more flexibility to skins:

http://minecraft.gamepedia.com/1.7.6

• Right and left arms and legs are now editable independently
• Uses a steve.png file with new layout and new dimensions
  • Dimensions for the file are now 64×64
• Overlay now includes the whole body
• Overlays are called hat, jacket, sleeves and pants legs
• Backwards-compatible

from http://www.reddit.com/r/Minecraft/comments/1vd7ue/new_skin_layout_explanation_in_comments/, old is 64x32, new is 64x64:

Zoom in to see better. Since the last snapshot (14w03) you can have separate texture for your left and right limbs. Also there is a 'hat' or 'armor' layer for all body pats, not only the head.
The 'armor' parts are marked with a '2'. They can be transparent of course.
LL - left leg
RL - right leg
LA - left arm
RA - right arm
This is the actual size you have to upload it in, so if you change this it will work! Also, if your skin is of the old size it will still work as it did before :)
EDIT: a better version by luci999: http://i.imgur.com/kZ6r4Ks.png

A guide to proper conversion process (if you just copy, the textures won't look proper): http://www.reddit.com/r/Minecraft/comments/1vfugk/guide_a_better_guide_to_updating_your_skin_to_the/ - http://imgur.com/a/hfaqL

another guide,
from the same thread:

The issue names no files, tests, or entry points. Start by locating the skin-loading and mesh-generation code, then compare its current 64x32 handling with the described 64x64 layout. Done means supporting separate limbs and full-body overlays while preserving backwards compatibility with old skins.