Update libfx2.

Add GlasgowBase.{get_verilog,get_bitstream}() shortcuts.

Always enable I/O buffers on startup (until alerts are implemented).

Fix typo that inverted OED bits.

Fix Mouser_PN for R19, R22. Closes #32.

bom2mouser.xslt: exclude components without Mouser_PN from output. Also, sort by Mouser_PN.

Fix ENVA/ENVB pin polarity (oops!)

Implement configuration of I/O buffer voltage. This doesn't actually work right now because of a schematic issue.

Fix DAC addresses on schematic.

Pulse ACT LED when there is USB activity.