Make Gen7Board-AVR 1.5 release.

 - The USB adapter is now on the main board. Pretty much what's
   on the ExtentionBoard-USB-B already, making this obsolete.

 - Noise cancelling coil for AVcc now 10 uH. This makes Gen7
   compatible with firmwares supporting LCD displays. Previously,
   hooking up a display would trigger the brown-out-detector often.