improve documentation
remove RewriteBase line

that RewriteBase line brought us a 500 on a webserver where we don't have access to the error-logs. No idea what the issue is. No idea whether other systems will have a problem because we're removing it. My limited testing showed no problems.
Merge commit '4e8df4168390220b17789e28113c84e5f8d37b4d'
hack to disable support for HTML tags in markdown formatting