fix the processing of the month and year fields in the SCTC
Timestamp (the month is 1-origin, so subtract 1 from it before
putting it in "tm_mon", which is 0-origin; the year is a 2-digit
field that is, at least, Y2K-safe (but Y2.1K-unsafe), so if it's
less than 90, assume it's in the 21st century);
UCP OT 50-57 messages have a fixed number of fields and a
special handling of the MT is not necessary, so get rid of that.
Also, fix a typo in a comment.
svn path=/trunk/; revision=4030
on the location of the UCB_ETX, is greater than the length of the tvbuff
- that can never happen, as the UCB_ETX is, as it was found, definitely
inside the tvbuff.
svn path=/trunk/; revision=4010