SQLite: Fixing sqlutil functions. Scope revision (Table, Source, Tx, Result should not be exported), mild golint review (unused/uncommented globals).

Applying the same style fixes as in #19: Running goimports (https://github.com/bradfitz/goimports) and Fatal(err) instead of Fatalf(err.Error())

Separated stdlib imports from other imports.

Adding a new error that will fire when trying to use One(), All() or Next() without closing the initial result set.