Don't break bottom ground plane if avoidable

[marcusmueller]

Would've done this as a quick PR, but alas, my KiCAD's too new, doesn't allow me to save as your file format :(

So, here's what I'd change:

Looking at this, the via between C3 and the FTDI IC is probably superfluous / ill-advised; I should've moved C13 closer to the IC.

The 12 Mb/s USB data lines aren't very fast, so I presume that the coupling when routing them below the other line (R3) isn't that bad.

[dkozel]

Ah! I like the sneak under the resistor. I'm assuming that the USB 1.1 traffic is going to be really resiliant to small routing faux paux like this.

Also yes, the other routing changes look good as well. I did pay attention to the splits in the ground plane and avoided them in the power converter section. That doesn't mean they shouldn't still be avoided where pragmatic.