spla print parameter test and config file improved —

Founded spla print parameter test and config file improved models & stl files for printing
Retraction Test
Marteinn - 3DP Iceland
My Stoopid Test Cube
MyStoopidStuff
Nema 17 Stepper test rig
PrintSideways
Thin Walls Test Piece
Breaks'n'Makes
Overhang Test
tomi3d