Added preview for

- Video (HTML5)
- Audio (HTML5)
- PDF (Browser capabilities)
attachment.
Added drag & drop functionality
Added attachment preview to preview before submitting

cfg/conf.ini.sample

@@ -64,7 +64,7 @@ languageselection = false
 ; scripts or run your site behind certain DDoS-protection services.
 ; Check the documentation at https://content-security-policy.com/
 ; Note: If you use a bootstrap theme, you can remove the allow-popups from the sandbox restrictions.
-; cspheader = "default-src 'none'; manifest-src 'self'; connect-src *; script-src 'self'; style-src 'self'; font-src 'self'; img-src 'self' data:; referrer no-referrer; sandbox allow-same-origin allow-scripts allow-forms allow-popups"
+; cspheader = "default-src 'none'; manifest-src 'self'; connect-src *; script-src 'self'; style-src 'self'; font-src 'self'; img-src 'self' data:; media-src 'self' data:; object-src  'self' data:; Referrer-Policy: 'no-referrer'"
 
 ; stay compatible with PrivateBin Alpha 0.19, less secure
 ; if enabled will use base64.js version 1.7 instead of 2.1.9 and sha1 instead of