Feat/input parser and formatter

[mmannes]

This PR resolves issue #129 by adding optional callbacks to Input and InputNumber components. The parser callback converts user input to the desired signal format, while the formatter callback presents the signal value to the user. You can check it working in the Docs.

[luoxiaozero]

Should we consider putting parsing and formatting into the onchange event, as this will avoid cursor confusion?

[mmannes]

Should we consider putting parsing and formatting into the onchange event, as this will avoid cursor confusion?

I like real-time formatting so much, specially when typing only numbers without having to go for the "." or "," key. But I think you are correct, the cursor confusion makes it impossible to fix a typo without rewriting everything.

I will do the changes you proposed and open another PR.

Thank you very much!