Fix sendMSDP() to allow variable values

See http://tintin.sourceforge.net/msdp:
"client - IAC SB MSDP MSDP_VAR "SEND" MSDP_VAL "AREA NAME" MSDP_VAL "ROOM NAME" IAC SE"
Merge branch 'release_30' into release_31

Fix sendMSDP() to allow variable values.
Merge branch 'release_31' into development

Fix sendMSDP() to allow variable values.
Use 'const QString&' for parameters.