Change echo to allow option of sql only

[Former user]

(original reporter: rtl) The echo option outputs every row of the result set as well as the original sql. For large result sets this can be too much information. It would be good to be able to specify echo=Off, Sql, All (or similar) to limit the amount of echo'd output.

[Mike Bayer]

in changeset:709, the 'echo' parameter can be True or False, which turns on and off query logging, or the string 'debug' which will additionally turn on result set logging. the unit tests have a default echo of True.