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