Rename TYPO3 to TYPO4 and change libraries accordingly
Many people confuse TYPO3 version 4.0 and later and speak of it as TYPO4. To accommodate these people and make their lives easier we should rename TYPO3 versions released since 4.0 to TYPO4. The new versions are thus TYPO4 1.0 (TYPO3 4.0), TYPO4 2.0 (TYPO3 4.1), and TYPO4 3.0 (TYPO3 4.2).
To make the step complete we of course need to rename class libraries like t3lib to t4lib and the typo3/ folder to typo4/, too.
Also thanks to the guy who already registered typo4.com for us!
(issue imported from #M7982)