added speed getters and setters and halt

[Poofjunior]

Tested. This can be merged.

Added:

• speed setter and getter
• halt function

The syntax is:

box = TigerController(PORT_NAME)
new_speeds = {'x': 0.5, 'y': 0.25, 'z': 0.75}
box.set_speed(**new_speeds)
# OR
box.set_speed(x=0.5, y=0.25, z=0.75)

You can read out speeds one axis at a time with get_speed(axis) like this:

for ax in ['x', 'y', 'z']:
    speed = box.get_speed(ax)
    print(f"{ax} axis speed is {speed}[mm/sec]")

to halt, you just:

box.halt()

I tested:

• reading the old speeds on xyz, changing the speeds, writing the new speeds, reading the new speeds, and confirming the change had taken place.
• sending a long move command, a halt command, and reading the position before and after to confirm that the machine had stopped partway through the move.

[Poofjunior]

ok, @adamkglaser if this works for you, I say we should

[adamkglaser]

Awesome! Will integrate these into dispim tomorrow in addition to flushing out CPX stuff with Nathan.