rs274ngc: back the rotary tool offset out of machine coordinates

[grandixximo]

Summary

G53 and the G28/G30 return are meant to reach a machine coordinate. Canon adds the G5x offset, the G92 offset and the tool offset to everything the interpreter hands it, so the interpreter has to subtract all three first. It does that for X, Y, Z, U, V, W and for A, B and C when the axis is wrapped. On an unwrapped rotary it subtracts the first two and not the tool offset, and canon still adds it.

So with a tool that carries a rotary offset, G53 G0 A0 parks the axis on the offset instead of on machine zero, and G28 returns to the stored position plus the offset. It is quiet because nothing disagrees: get_abs_position() adds tool_offset.a too, so #5024 reports the same wrong number that was commanded, and the error tracks the loaded tool.

59e57c0 added the tool offset term to every other coordinate when the offset became a nine axis pose, including the wrapped rotary case in the same hunks. The unwrapped one was missed, so this has been the behavior since 2009.

Change

Six lines. The else branch of the A, B and C cases in find_ends() (G53) and in find_relative() (G28, G30, tool change return) gains - tool_offset.<letter>, matching the wrapped branch directly above it.

#3969 adds a branch just above these same six else lines without touching them, so the two should not conflict beyond adjacency.

Behavior change

This does change what an existing machine does. It is a change in the correct direction, and it only bites if the tool table or G43.1 sets a nonzero A, B or C offset. Such a machine has been landing G53 and G28 off by exactly that offset all along, so anyone who noticed will have compensated somewhere else and will need to remove that compensation. Configs with no rotary tool offset, which is nearly all of them, are unchanged.

Test

New tests/interp/rotary-tool-offset, failing on master and passing here. With G43.1 Z5 A7 B11 C13 in force:

	#5024-#5026 on master	here
G53 G0 X1 Y2 Z3 A20 B30 C40	27, 41, 53	20, 30, 40
G28 to a stored 20, 30, 40	27, 41, 53	20, 30, 40

Nothing else in the tree is affected: no .tbl under tests/ has an A, B or C column, G43.1 appears in one test with no rotary words, and G10 L1 with rotary words appears nowhere in tests/ or configs/.