[daip] DCONV (fwd)

[Eric Greisen]

I have found a minor but significant error that caused the task to
ignore OPCODE.  I tried the task and it did not do anything desirable
for me.  I suspect that CONVL's deconvolution would be better.  I
found the help very irritating and the code neglects to test for
various things that can cause it to go haywire.  This is not a well
tested and regularly used AIPS task, but something experimental.

It will be corrected after 10 pm MDT tonight for MNJs.

Eric Greisen