Added reading and storing of the XMPP password of the current user.
Integrated QXmpp in the build system.
Added a basic version of the chat window.
Added time stamps to the chat. Enabled translations.
Moved the connection and configuration of XMPP to the log-in process.
Ensured messages are sent to the group chat rather than to individual
users.
Improved the adherence to code conventions after a code review.
Ensured messages are always aligned at the top to user names, and users
onine are deleted.
Changed the searcning for qxmpp to include debug libraries as well.
Ensured sent chat messages are always wholly visible.
Prevented empty time stamps - when less then a minute has passed - from
appearing.
Added a define to ensure the build works without qxmpp.
Patched the Qt CMake function for auto-translations so that *.ts files
are not deleted on clean.
Merge pull request #2249 from ddobrev/xmppchat

Added public chat based on XMPP
Merge branch 'master' of https://github.com/highfidelity/hifi