PRGA Release 0.3.5

• Added support for frame-based programming protocol
• Added support for memory initialization (ROMs!)
• Changed API so programming protocol may be selected after VPR/Yosys script
  generation, decoupling design space exploration with physical implementation
• Improved bitstream generation to a more generic FASM format and more flexible
  assembler
• Added "Magic" bitstream checker based on the Magic programming protocol to
  help debugging the bitstream loading process for other protocols
• Example scripts and documentation updated to match the modifications above