[mysql] match `columns` returned with latest AR 4.0 (collation, strict, extra)
[mysql] username defaults to 'root' on MRI
review HSQLDB/H2 explain - make sure prepared statements are used
doc: mark ExplainPrettyPrinter class as private
[mssql] `to_sql` on explain should receive binds as well
update exec_xxx tests for DBs that do not generate IDs (Oracle, Firebird)
update test_exec_insert so it's more 'portable' with formatted time values
re-build jar