Fix for bug https://github.com/codemirror/CodeMirror/issues/4897

Signed-off-by: Yvonnick Esnault <yvonnick.esnault@corp.ovh.com>

Closes #4892

Issue #4889

IANA registered application/vnd.coffeescript

Also noted the text/coffeescript option in the demo

Also .asc and .sig extensions

Re: http://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types

Seems Apache has its own list for non-registered
media types.

Issue codemirror/google-modes#8

Issue #4876

See #4872.

Closes #4869

Issue #4868

Issue #4864

This is opt-in, the plugin needs to produce message_html instead of
message to be rendered as HTML.

This should help developers building this functionality out that may not
realize they need to source the linting library seperately.

Issue #3059

Closes #4855