Merge branch 'master' into 'master'

Make luacheck happy

See merge request VanessaE/pipeworks!41

Merge branch 'm_small_fixes' into 'master'

Various small fixes

See merge request VanessaE/pipeworks!35

Merge branch 'master' into 'master'

Prevent the symptoms of Issue #33

See merge request VanessaE/pipeworks!31

add minimum minetest version key for contentdb

add signs_lib placement rules

only works on signs_lib commit dcdee222 or later.

Prevent another crash if minetest crashes during startup

depend on screwdriver

Merge branch 'rotate-metadata-fix' into 'master'

fix metadata loss on rotate

See merge request VanessaE/pipeworks!6

fix autocrafter recipe

license fixups: update to LGPL3.0 for code, add CC-by-SA 4.0 for media