makes backup copies of caravel and caravan layouts and replaces the
cell name of any gpio defaults block that is changed from the
contents of user_defines.v. NOTE: user_defines.v ultimately must
reside in the user project. The Makefile should copy the user's
version into the caravel directory space before running the script,
or else the script should be rewritten to reference the user's
project area when reading user_defines.v.
verilog/rtl/, and creates all the layout files needed to represent
all unique combinations of defaults used in the file. Not done:
Modifying the top level layout to use the correct defaults (because
the top level layout does not yet exist).
Tim Edwards