[Icons] Removing obsolete unused icons
[Icons] Build icon updated
[Icons] Toolbar status icons updated
[Icons] Toolbar status: updates available:
software-update-available-16.png → updates-available-16.png
[Icons] Toolbar status: failure, warning, ready:
status-error-14.png → status-failure-14.png
status-steady-14.png → status-ready-14.png
[Icons] Toolbar status: waiting animation (not used yet)