net-im/jsxc: New port

JSXC is a browser-based XMPP Client which suports video calls, file
transfer and encrypted communication

Features:

• Federated real-time communication with XMPP
• One-to-one conversation
• Multi-user conversation
• File transfer
• Video calls
• Internationalisation
• Desktop notifications
• End-to-end encrypted two-party communication
• Responsive layout
• Emoticons two_hearts
• Multi-Tab
• Screen sharing

PR: 268107
Reported by: manuel@mmap.at
Tested by: bofh
Approved by: mdw (Submitter is maintainer)