Added new sql connection type 'function' which delegates the creation of a connection to a function
Also added 2 new parameters to sql data files: keep.alive which when set to any value will
prevent the call to dbDisconnect; and prequeries which will issue multiple queries separated
by a semicolon using dbSendUpdate (useful for creating temporary tables)
Modified reload.project() so that it re-sources the .Rprofile file after cleaning the environment