Corrected bugs in Qsl_Rcvd.ModifyValues, and renamed to
ModifyValues2 because these modifications must be performed after
QslRDate.ModifyValues is called.
Added QslRDate.ModifyValues to check value of Qsl_Rcvd
for "Y", "I" or "V". If not found, delete QslRDate from Qso.
Updated user manual to document this.