Blender Git Loki

Three-fixes-in-one:

#5417: Only Shadow material gave shadow outside of Spot bundle
#5414: Material Nodes: sockets without input were always treated as single
value inputs, ignoring color or vector. (Caused by commit to do
automatic conversions of socket links).
#5420: When reading with old Blender a new file that has a new window type,
saving it over, and read back in current Blender, the window type
should be reset to EMPTY, because all its data got lost.