Merge pull request #1 from kaeza/master

Fix image files being left open and made id a local variable
Add preview generator (requires blender and shell), and previews for default skins.
Use previews in the mod; Move previews to .previews so it isn't considered as a mod by minetest.
Add default to dependencies
Update original skin, give previews a transparent background and update generate_previews.sh
Add sheriff skin by Chinchow
add more skins
update skins
Merge pull request #3 from HybridDog/master

add more skins
Add 4 new skins by jordach, and regenerate all previews
Add an image for Inventory plus+
Add 2D oerkki skin
Add cisoun's skin (2d)
pngcrush all skins (previews will come later with a script update)
Update previews; the script now uses pngcrush, names don't have a double extension and previews are displayed in "your current skin"
Add back previews
Strip metadata from previews (will allow updating 3d skins without re-uploading all previews)
Update Jordach skins (4 new skins, 2 modified)
UI update
Display all skins in the same list (so we have less pages), and show pages count