Merge branch 'z411/team_queue' into 'master'

Create queue system to prevent team imbalance in teamplay

See merge request xonotic/xonotic-data.pk3dir!1093

diff --cc qcsrc/server/client.qc
Simple merge

diff --cc qcsrc/server/command/cmd.qc
Simple merge

diff --cc qcsrc/server/teamplay.qc
Simple merge

diff --cc qcsrc/server/world.qc
Simple merge