TYPO3 Core

There's lots of chr(10), chr(9) as well as magic numbers like 3600 and 86400 strewn all over the code. Let's define some constants for this which
1. make the code a lot more readable
2. make the code a tiny bit shorter
3. will improve performance a tiny little bit because it removed the PHP function calls to chr

These are the constants which this patch adds and includes them in init.php and index_ts.php:
CR
LF
TAB
CRLF
ONE_HOUR
ONE_DAY
ONE_WEEK

The patch is mostly search'n'replace with the manual corrections and improvements (e.g. 24*ONE_HOUR has been changed to ONE_DAY, and 7*ONE_DAY has been changed to ONE_WEEK).

(issue imported from #M12066)