Add NumberInput widget

[hangleang]

Hi there. This is the implementation of NumberInput widget. Sorry for committing lately, I was very busy on my work recently.

Feel free to give me some idea to improve this widget. Thanks you guys....

[Kaiden42]

Thanks for your PR! 🙂

Sorry for committing lately, I was very busy on my work recently.

Don't worry, I was busy as well.

Looks pretty good so far. However, I have two small suggestions for improvement:
I saw that the new number_input widget depends on the crate num-traits. Could you, similar to the crate chrono, mark this as optional? For the number_input feature you can then say that it depends on the num-traits "feature". Similar to the date_picker feature. This way the dependency will only be compiled if the number_input feature is enabled. You can read more about this here.

Additionally, have you thought about floating point support? These are currently only partially supported. I was able to change the type of the number_input example from u8 to f32, but it caused strange effects. I am not able to enter a decimal point into the field myself, but I am able to generate floating point numbers via the increment/decrement by setting the step size to 0.5. If I then delete the decimal point, I even get beyond the maximum value.
Example: I set the value to 26 and increment by 0.5. This gives me 26.5. If I now remove the decimal point I am at 265, whereas only a maximum of 255.0 is allowed.

[hangleang]

Done 😀

[Kaiden42]

Awesome! Thank you for your work. 🙂

I've now merged your PR. However, I noticed two minor issues, but they can be addressed in the future.

• With decimal support I'm not able to type the decimalpoint at the end of the number. This could be caused by the cut-off of the ".0" decimal.
• Support for web would be great in the future.