Fix typos in several documentation strings.
Fixing more typos.
export Tx
Merge pull request #28 from sqs/export-Tx

Export (Transaction).tx *sqlx.Tx field
Merge pull request #25 from victorkryukov/doc-fix

Fix typos in several documentation strings.
Support embedded structs (closes #13)
Handle auto-increment columns in or after embedded structs

Fixes issue reported by @cryptix at
https://github.com/jmoiron/modl/pull/17#issuecomment-55384738.
DropTablesIfExists