add new option to labels: 'consistent'

[gvwilson]

It would be good to have an option to have the number of decimals in axis labels behave consistently.

Current default:
10
12.5
15
17.5

Desired outcome:
10.0
12.5
15.0
17.5

Proposed change:

Add a new option to tickformat parameter named 'consistent', which will make sure that the number of decimals is always aligned.