long press the delete button to delete all digits

[Wjxfi]

this has already been done https://github.com/Darkempire78/OpenCalc , and I find it very convenient (Helps in solving big math examples)

[Yet-Zio]

@Wjxfi sure, I will add that in the coming update.

[praveenrajput]

@Yet-Zio are you working on this or can I fix it?

[Yet-Zio]

@praveenrajput Im having exams, so I didn't start work on it yet. But sure, you can add it! :)

[Yet-Zio]

Added and improved as of #44