index: decode xmpp%3a uri if encoded

URIs: Add Contact Invitation with IBR

URIs: Add register URIs

URIs: Support group chat uris

Android clients: Only use F-Droid links

readme: Update for fork

recommend text: Put OS name inline.

index: Rewrite in PHP

de.json: shortened clients text

en.json: minor typo fix

fix styling

Fix Xabber URL

Update en.json

Use switch/case instead of else if statements

And add XMPP logo at the buttom of the page

Add some changes and new order of tags

Add list of apps for Windows

Add list of apps for Mac

Add list of apps for Tizen

Add Converse aans Psi

Add monocles chat