This project contains the SRAM peripheral (as in Lab 6) and reads/writes
it from the C code.  Also displays a checkerboard pattern as a test of
VGA writing capabilities and the way the timing of a screen draw works.

Important changes:

data/system.ucf -- pins for the SRAM added
system.mhs -- SRAM ports added
system.mss -- added driver for the sram_peripheral
directory pcores/opb_sram_v1_00_a -- contains the SRAM peripheral
  data/opb_sram_v2_1_0.mpd
  hdl/vhdl/opb_sram.vhd

sram_incl.make -- makefile to download data to the SRAM
Makefile -- include the line "include sram_incl.make" to enable the 
above
