By now this was only possible by adding small patches to minetest, don't know if they make it to master as they break the "a block is a block" rule ;-)
Use crowbar to increase removal speed of door by factor five
crowbar reciep:
. . steel_ingot
. steel_ingot .
steel_ingot . .
Working (>0.0.2):
-placing doors relative to player position and position of door (4 possibilitys)
-opening/closing doors
-removing doors
-doors are as slim as their collision box and smaller than block size -> fixed by minetest patch "cube_disorted"
-transparency does work (->github/sapier/minetest branch sapier_experimental)
-doors can't be walked through if closed (->github/sapier/minetest branch sapier_experimental)
Problems:
nothing known
Changes:
Version 0.0.3
-Iron door added
-switched from 2 entities per door to 1 entitie
-fixed dig door bug
-switched to left click door opening
Screenshots:
-closed door

-opened door (you can see the thin black line of the collision box around the frame)

-all in one

Minetest Patches
transparency patch is not mandatory and may have side effects to other parts of minetest, haven't checked this
http://www.mediafire.com/?8xxzdcvxs56ze3z
cube_disorted patch adds another visual style to entitys using their collision box for drawing the mesh, beware collision box HAS TO BE MinEdge,MaxEdge to get reasonable drawing results!
http://www.mediafire.com/?i0zqkntbnzt7jog
Mod:
http://www.mediafire.com/?khcvdbcq1abzwvx (Version 0.0.1)
http://www.mediafire.com/?0peyua24rdc6mia (Version 0.0.2)
http://www.mediafire.com/?4e8of77m8ah602x(Version 0.0.3)
