[TYPO3-core] RFC: #13262: replace hardcoded typo3/ with TYPO3_mainDir

[Georg Ringer]

Franz Holzinger schrieb:
> it would be helpful to have a common TS constant for the typo3 folder.

What has TypoScript there to do? This bug is about something else:
Giving a simple option to change the URL to the backend.

Please use a list like dev or the general list to discuss possible
features and not the core list

Georg