Add CH340G USB to UART Converter

Unofficial CH340G translated datasheet: www.datasheet5.com/pdf-local-2195953 Official CH340 English datasheet (no CH340G): http://wch-ic.com/downfile/79 Official CH340 Chinese datasheet (including CH340G): http://www.wch.cn/downloads/file/79.html Screenshot (updated for commit bc12df27) The layout is based on the unofficial datasheet with a few modifications to make it more consistent with other KiCad symbols:

• VCC and GND on top and bottom
• UD+ and UD- to D+ and D-
• D+ and D- near center of left side
• D- above D+
• R232 configuration pin on left side

V3 is meant to be connected to VCC when VCC is 3.3V, or simply a decoupling capacitor to ground when VCC is 5V. I set its electrical type to "passive", but I am not sure if that is right.

---

Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• Provide a URL to a datasheet for the symbol(s) you are contributing
• An example screenshot image is very helpful
• Ensure that the associated footprints match the official footprint library
• If there are matching footprint PRs, provide link(s) as appropriate
• Check the output of the Travis automated check scripts - fix any errors as required