RangeEditor does not behave consistently for wx and Qt

The RangeEditor behaves differently depending on if Qt or wx backend is used. The differences are listed below:

* Qt never use the 'auto_set' feature, which means it can never automatically update the value for every key stroke in the text editor which wx can.
* Wx can either update the value only on lost focus or a combinaton of lost focus, pushing the enter or tab keyboard in the text editor (the 'enter_set' feature), while Qt will only update on the combinaton of lost focus, pushing the enter or tab keyboard.
* Qt truncates the value copied or typed to the text editor silently, while wx shows an error message and color the background of the text box red.