format: Sanitize format name in the format factory

RSS-Bridge currently sanitizes the format name only for the display
action, which can cause problems if other actions depend on formats
as well.

It is therefore better to do sanitization in the factory class for
formats. Additionally, formats should not require a perfect match,
so 'Atom' and 'aToM' make no difference. This will also allow users
to define formats in their own style (i.e. only lowercase via CLI).

References #1001

actions/DisplayAction.php

@@ -18,12 +18,6 @@ class DisplayAction extends ActionAbstract {
 		$format = $this->userData['format']
 			or returnClientError('You must specify a format!');
 
-		// DEPRECATED: 'nameFormat' scheme is replaced by 'name' in format parameter values
-		//             this is to keep compatibility until futher complete removal
-		if(($pos = strpos($format, 'Format')) === (strlen($format) - strlen('Format'))) {
-			$format = substr($format, 0, $pos);
-		}
-
 		// whitelist control
 		if(!Bridge::isWhitelisted($bridge)) {
 			throw new \Exception('This bridge is not whitelisted', 401);