ccdbig: Use the CCDPACK include file directly

via a softlink. Rather than using an explicit copy.
ccdbig: Initial versions of autoconf build files
ccdbig: Use PRM rather than DCV

DCV was removed in 2012 with commit
b0e36f285f1c2df6d948fef05aec0537542d1fa8 so now the code
uses NUM_ conversion routines.
ccdbig: Fix compiler warnings

Some of them were of the form:

if ( a = b ) {
   ...

where some needed to be == and others needed to be (a=b). Hopefully
the right choices were made.
ccdbig: Basic builds work and uses IFD
ccdbig: Data files have moved to share/ dir
ccdbig: Add welcome message to init script
init: Add ccdbig
ccdbig: Tweak welcome message
ccdbig: Port to 64-bit CNF %VAL
ccdbig: Delete trailing whitespace
ccdbig: No longer need idset command
ccdpack: Do not need private PDA file if linking against PDA
Merge branch 'ccdbig-fixes'

+ ccdbig now builds with autoconf
+ Uses IFD file to create init scripts and IFL file
+ init has been taught about CCDBIG
+ Port to 64-bit
pda: Fix bug in pda_rnnor

Use correct range in initial check to be > 0.5 instead of >= 0.5.

Manual application of patch from CCDBIG that was committed in
commit ae4b42275ddd76ceda178fc85e4ec2366fdd2645 from July 1998.