[TEST PR] New scale test for auto skipper.

[KoyoSE]

Note: This is a test code for auto skipper. Please use it for reference.
(Reference #3233 )

I tested the display method not using auto skipper.
For testing, the code is not beautiful.

Summary

Extend Chart.Scale etc.
Two scale type ( linear2 and linear3 ) were added.
Fixed several bugs on the current Chart.Scale.
A sample html was added.

linear

Run the original linear scale type with extended Chart.Scale.
This means that the existing scale will work.
Other existing scales also work.
In this case, autoSkip is used.

linear2

Display the scale in a way not using autoSkip.
Ticks are divided into three levels to control label display.
I adjusted it display close to the original linear.

linear3

It is a scale that changes the scale calculation parameter and reduces the number of tick marks.
This will be useful for displaying fine scales.

jsFiddle

It was harder than I imagined. 😅

[KoyoSE]

Additional notes : When min max stepsize is set, I think linear scale is correct. The step should start from min. 😃
https://github.com/chartjs/Chart.js/blob/master/src/core/core.ticks.js#L68-L75
I forgot this code.

[KoyoSE]

Changed

jsFiddle

My opinion

linear2, linear3, the display of the scale is fine and it is not simple. To merge with the original, adjustment is still necessary.

[KoyoSE]

@etimberg
Please close this PR whenever you like. 😃