Case-insensitive matching for peripheral and register names

[carlnorum]

Tab completion is already case insensitive, but if I type the whole peripheral or register name, it doesn't work. I hacked in something by using 'upper()', but it wasn't very good. I also tried to subclass OrderedDict to make a case insensitive version, but I'm not good enough at python and I had to give up for now. I just wanted to file an issue so I'll think about it again in the future.

Suggestions for how to best implement much appreciated!

[bnahill]

Hey Carl,
Sorry for the delay. I've been a bit overwhelmed with unrelated projects lately. Anyways, I really appreciate your contributions thus far and will leave this open to look into it when I get back into the software side of things.

[carlnorum]

No problem, and thanks for merging the other pull requests!