More user-friendly installation with a warning for missing .htaccess #5

It would be great to start to use index.php for the HTML interface.

This interface should also check the proper installation - including the test of URLs (already done in the tileserver.php) and of the availability of .htaccess file.

Ideas for proper .htacess tests:

• check file by is_readable(".htaccess")
• print_r(apache_get_modules()) will show you the loaded Apache modules (only if PHP runs as a module as well)
• use "SetEnv TILESERVER ok" in .htaccess and "$indexUrl = getenv('TILESERVER');" in PHP.