As we now use Sequel as the underlying SQL layer, we already get the column values in the right type and no longer need to support type conversion. Therefore, all the 'vprocs' related code was removed.
Added a 'create_table' to OmlSqlSource to simplify the binding of a database table to a OmlTable. See 'hello_database.rb' in the omf_web tutorial. Also changed the way for omitting the OML headers in that process. Not sure if that is breaking any code out there. Finally, added a 'query_interval' to SqlRow to slow down consecutive queries to the database when using 'limit' to scan through a large result set. Most useful for 'replaying' measurements. Most likely should add a 'pseudo-realtime' mode where we take the actual timestamps to space out row insertions.