Merge pull request go-pg#1400 from go-pg/fix/deprecate-sql-tag

orm: deprecate sql tag

Cleanup

tx: fix closed

Merge pull request go-pg#1395 from go-pg/fix/tx-close

Add Tx.Close

internal/structfilter: fix test

Merge pull request go-pg#1378 from go-pg/feature/union

orm: add support for unions

Merge pull request go-pg#1356 from rocurley/v8

Backport go-pg#1329 and go-pg#1331 to v8 branch

Merge pull request go-pg#1347 from go-pg/fix/set-deadline-error

internal: return an error on setting deadline error

urlfilter: replace url.Values with urlfilter.Values

urlfilter: rename SetValues to Decode