psLookupTable & partially constructed tables

[David.Robbins@…]

it's unclear how the psLookupTable functions should handle a case where an input
table has a partially constructed row. For example:

#
#psF32 psU16 psU32
-10.05 2 4
3500.67 8 16
10000.1

Currently no errors seem to be reported for this case but there is a resulting
memory leak. The documentation doesn't seem to include this case.

[Paul Price]

I think this is a reasonable condition to produce an error. I updated the SDRS:

If the input file does not conform to the expected format (e.g., not enough
columns in a row) the function shall generate an error and return \code{NULL}.