repaired nut.blt

It appears that somehow data about a fork got rolled into the file.
Began adding a model for the hex class
Merge remote-tracking branch 'origin/master' into solidworks
Merge remote-tracking branch 'origin/master' into add-hex
Merge remote-tracking branch 'origin/master' into add-hex

Conflicts:
	data/nut.blt
added missing type
quarantined hex_socket.blt while working on hex.base

something wrong with the types
Merge branch 'master' into add-hex
Added model and base for hex screws

hex.blt still needs pitches defined for coarse threads
Merge remote-tracking branch 'origin/add-hex' into solidworks
Ignore hidden SolidWorks temporary files
Merge branch 'solidworks'