Ultimate7e tutorial: Processor upgrade

Victzh has the gist of it. While the end of life of the 7e is irrelevant (Deviation is primarily designed for the Devo line), there is no comparison between the effort needed to add the 4-in-1 module to an AT9 vs doing the ultimate 7e mod. In a sense the only reason I provide pre-built binaries is because I don't think most users can go through the steps to build from source. But if you can replace the MCU on a 7e, I have confidence you can learn to setup docker and build from source, and so the incentive for me to support it is lower. Additionally, with such a major mod, it is very easy for user error to cause issues which there is no way for me to support. I don't really want to deal with bug reports that I cannot reproduce, and so, again, a custom build doesn't make too much sense. Lastly, There are many additional hardware mods that can be done for the 7e (analog dials, additional switches, etc). While we can enable all of those as options, not everyone will use them, and again support becomes a real issue.

I may eventually cave and officially support the ultimate 7e, but I am not there yet.

Note that I merged slipstream's mods into the trunk. So you will get the changes there as well. Along with the bugs from the menu re-org that are still in progress.