Convert kcd to DBC: No "GenMsgCycleTime" records

[MamoruAsagami]

When you convert from .kcd to .dbc, message cycle time info is lost.
Message cycle times are coded as Message.interval as in <Message ... interval="100"> in .kcd, which should be transformed as below in .dbc.

BA_DEF_ BO_ "GenMsgCycleTime" INT 0 0;
BA_DEF_DEF_ "GenMsgCycleTime" 0;
BA_ "GenMsgCycleTime" BO_ <can id 1> 100;
BA_ "GenMsgCycleTime" BO_ <can id 2> 50;
...