Feature Request: Reset task nubmer

[KevCui]

Is your feature request related to a problem? Please describe.
For example, If I created 3 tasks, they are:

1. task 1
2. task 2
3. task 3

Then, I delete @3, and create a new task 4. The new task will be created as number 4

1. task 1
2. task 2
4. task 4

I can imagine if I use taskbook for a long time. I will have maybe only 1 task in the list, but its number could be @99999, which is a bit inconvenience to type more digits.

Describe the solution you'd like
Is it possible to separate task id (which is unique in json) and task number (showing in the list)? And task number is recyclable, for the case above, it should show:

1. task 1
2. task 2
3. task 4