* improvements to sqlite source metadata query
* table metadatawriter colorization tuning; minor testh.Helper refactoring
* cleanup of metadata for multiple drivers
* more cleanup of source/table metadata
* yet more cleanup of source/table metadata
* improvements to mysql SourceMetadata
* improvements to mysql TableMetadata
* yet more fiddling with mysql metadata
* initial refactoring for the numRows param
* work on driver.NewBatchInsert
* work on NewBatchInsert
* batch insert seems to work
* switched testh.Insert to use BatchInsert
* doc cleanup
* batch insert for dbwriter and csv
* removed unneeded NumRows from driver.StmtExecer
* minor tidyup