Openxc7 Tetrisaraj

Demo of how to use https://github.com/openXC7 tools (yosys+nextpnr-xilinx) to implement the HW side of a custom SoC with RISC-V CPU & our special Video Controller in Basys3 Artix7-35T. Complemented with SW in the bare-metal 'C' they, together, make for this classic game. Except that it's now, in the standard BiH tradition, with a twist of our own.