magic database derived layout of a cell that declares GDS_FILE
but for which the GDS file referenced cannot be found or read.
This will produce an incomplete GDS file instead of an apparently
good and complete GDS file that actually contains bad data. Also:
Added new command "random" that allows a random seed to be set,
for use with the GDS output when writing a full dump of a GDS
file. Otherwise, the output prefixes are always the same, which
defeats the purpose of adding the random prefix.
Tim Edwards