Fix documentation of SQlite3Adapter.columns

As of https://github.com/rails/rails/commit/e781aa31fc52a7c696115302ef4d4e02bfd1533b SQLite3Column has been dropped.
Remove references to SQLite3Column from documentation
Fix that render layout should also be picked up by the template dependency tracker, but only half-ways. You can add that layout option on the same render call, and both templates should be added to the dependency tree. But thats going to require a more serious rework of the tracker. Please do help fix this part of it too. For now, render layout needs to be on its own line.
Fix protect_from_forgery docs
No verbose backtrace by db:drop when database does not exist.