[TASK] Add default security settings in .htaccess

Add a new security section within .htaccess to help users secure their
TYPO3 install:

- Restrict access to deleted files in Recycler directories
- Restrict access to TypoScript files in default templates directories
- Restrict access to Private extension directories

Resolves: #28368
Change-Id: I94c09f50616af55cfdd9577097251692b2111ae7
Reviewed-on: http://review.typo3.org/3462
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer