Convert UD3.1c PCB source files to KiCad

[lelahx]

I have converted the UD3.1c design files to a KiCad project, as I believe any open source project should ideally be made with with open source tools, or at the very least be open to contributors who don't have access to paid software.

This is a first draft of a conversion, but I believe it to be fully working. I'll report back on it once I get it made and build it though!
Almost all the Altium schematic symbols are replaced by their equivalent KiCad counterparts, and I've also replaced Altium footprints by KiCad standard library ones where it was easily applicable. The routing and layout is for now almost entirely the same, and as such I didn't deem it necessary to call this version a new name, so it is still a UD3.1c in my book!

The next step would ideally be to replace the 0603, 1008 and 1210 resistor and capacitor SMD footprints by the standard KiCad ones, but it seems that it would require quite a lot of manual work and a rerouting of all the traces, and I frankly don't have the time for that (for now anyways). So I just stuck with KiCad-converted Altium footprints for now. Maybe I'll get to it someday, but in the meantime if anyone wants to have a go at it I would be glad!

I believe this PR is mergeable in the current state, but I'd totally understand if you think it still needs a bit of work. I'm just happy to put this out there for the community, and would hate for these files to just rot on my hard drive!

Anyways, thanks for reading me. I'm of course open to any questions and suggestions regarding this!

[TMaxElectronics]

Thanks for the effort of converting the Project :) I didn't have the time to do so, but I totally agree with you in that the project should be usable with open source software.

I'll be happy to merge the pull request once you got your boards and verified everything is ok, although I'd like to keep the Gerber folder in the root directory so its easy to find even without looking at the release page ;)

[lelahx]

I finally received my boards and started building the beast! I don't have all the components yet, as a few errors were made in my order so I can't test it for now.
Anyways, while building it I noticed that a few components' values were undefined, namely R1, C86, C93. What should I do for those? Also, there's a lot of PCB jumpers on there and I don't really know which ones I should bridge ^^
Appreciate any help, thanks in advance!