Updated connection interface
Removed extra line
Restore the ability to easily override the compilers
Table prefix was added twice

If a table prefix was set in the database config, this code caused the prefix to be added twice: once here and once in the call to the database engine inside `DatabaseSessionHandler`. refs #4580 on the correct branch.
Merge pull request #4609 from kohenkatz/4.2

Table prefix was added twice
Merge pull request #4605 from GrahamCampbell/4.2-views

[4.2] Restore The Ability To Easily Override The Compilers
Merge pull request #4604 from GrahamCampbell/4.2-db

Updated Connection Interface