Small fixes and alternative components.
- Added SMA washers (#74)
- Added note with max and recommended sma input level (#83, #100)
- Changed C3 to a higher voltage rating (#87)
- Fixed #93
- Changed LD14 (#67)
- Fixed #96
- Added PCA9539 as an alternative GPIO expander
- Added switching frequency selection to IC7
- Added LT1938 as an alternative to TLV62150
- Added additional I2C bus dedicated to 24AA02* EEPROM on FPGA pins P19 and P20 (#97)
- Removed unused DDR3 DQ termination resistors from FPGA_SDRAM (they weren't placed on the PCB, they were just on schematics)
- Updated version number in schematics
- Moved 712RA connector back 0.5mm
- Updated copyright year