Allow "-" as character for identifier in caching framework
The caching framework contains the allowed characters that can be used for identifiers.
Since this part was backported to TYPO3 4.3 there's an issue with using the caching framework on pages with negative page IDs (e.g. "-1"). Therefore a identifier like "pageId_-1" would be defined which is not allowed.
In TYPO3 4.3 context this occurs in the context of workspaces/versioning.
The dash "-" is currently used in the file backend as separator.