Merge "Added new cl_hooks, menu_cmd isdemo and fixed demoseeking.cfg"

Source branch: 'drjaska/demohooks'
Target branch: 'master'

Closes #2970

See merge request xonotic/xonotic-data.pk3dir!1254

diff --cc commands.cfg
Simple merge

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

diff --cc qcsrc/client/main.qh
Simple merge

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