Adjustable 2020 End Stop Bracket

This end stop bracket is modified from
https://www.thingiverse.com/thing:602730. It is an end stop bracket for
attaching MakerBot-style end stop switches to 2020 extrusions. It makes
changes intended to solve two problems:

* My end stop switches have seven solder joints on their backs, three of
which bumped into plastic on all the end stop switch brackets I saw on
Thingiverse, thus inducing strain and rotating the end-stop switch
outward. This modified design includes three holes