use command in cpymad

[Eothred]

The use command can break a lot of stuff, so it should not be used as heavily as it is currently the case in cpymad.

One example being after aperture, where the aperture call completely ruins the sequence as far as I am aware. A different case is after errors have been assigned, where use will reset the errors again.

Some kind of auto_use flag that can be turned off might improve things. This is generally a problematic limitation in madx