scorbot-er-3: sleep less between updates to the arm

Signed-off-by: Sebastian Kuzminsky <seb@highlab.com>
scorbot-er-3: warn on serial errors

Signed-off-by: Sebastian Kuzminsky <seb@highlab.com>
scorbot-er-3: set up for getting scale from ini

It's not just input-scale, really, so just call it scale...

I don't know what the scales should be yet, so i'll just keep them at
1000 for now (same as before).

Signed-off-by: Sebastian Kuzminsky <seb@highlab.com>
scorbot-er-3: fix motor move commands

Signed-off-by: Sebastian Kuzminsky <seb@highlab.com>