iface.widget: add TrackingLabel

Which proudly tracks content of a field in an object in real time. Be ready for exceptions though.

Signed-off-by: mkhropov <mkhropov@gmail.com>
iface: new menu to show elem stats

For now contains only it's coordinates. AND is bugged somehow - first label (X:) is drawn black. It's a generic text bug, I don't worry about it much for now.

Signed-off-by: mkhropov <mkhropov@gmail.com>
iface.widget: Label little fix

Height was too big

Signed-off-by: mkhropov <mkhropov@gmail.com>