Fwretract fixes, cleanup

I fixed the fwretract z-lift function and moved the fwretract code to a function so that autoretract (which was even more horribly broken) can use it too. Autoretract is also now disabled by default, so that it safe to enable fwretract by default, with autoretract only enabled by M209. I also moved the fwretract defaults to configuration_adv.h, below the line that enables the feature.

The default settings will no longer change the behavior of machines where G10/G11 and M207-209 are not used, and it is now safe to enable FWRETRACT in the default configuration to make them available to those who want to use them.