Tweak to .htacces file

This changes .htaccess directive from `FilesMatch ` to `Files ~ `.
Result is exactly same, but FilesMatch is not supported by IdeaWebServer, which is a apparently fork of Apache 1.2.x. where it was not available either.

IdeaWebServer is used by few hosting companys in Poland.

I've also added a note about the requirement for .htaccess in the README.md because without it admin would now work (didn't try).

By the way, what for are file extensions sdb|s3db|db?