v4.0.1

• merge all USB entries into one
• add (disabled) tag in menu
• interface modification
• version bump to v1.3
• add PXE and USB enable options in menu
• add PXE to bootorder menu
• change interface to lower case
• version bump to v1.2
• change letter for save and exit to S
• use proper way to access extended SPI registers
• add support for yangtzee fch spi controller
• user interface improvements
• add PC Engines header
• add README and Makefile
• initial commit based on
  apu1coreboot_140908