ref #79 Remove GenericListProperty
remove GenericListProperty
improve ListProperty
ref #79 visit() -> accept()
rename visit() to accept() to match visitor pattern naming
ref #79 More Signals
add signals to ListProperty
move changed signal up to ValueProperty
ref #79 Remove Children
Properties no longer have children
ref #79 add Widget for LimitedProperty<float>
ref #79 Improve widget for LimitedProperty<int>