Add template inheritance and template insertion (see #6508)
Add the templates folder to the `.gitignore` file
Do not create the date ranges in the `Date` library by default
Do not insert files from `$GLOBALS['TL_JAVASCRIPT']` twice (see #6920)
Remove the inline `float:*` styles and use the float classes instead (see #6851)
Fix the "getFrontendModule" hook (see #6921)
Add a `Template\Base` class to centralize shared logic
Update the `autoload.php` files