Fix Drawable LineChart Fill Bug

[giantramen]

PR Checklist:

• [x ] I have tested this extensively and it does not break any existing behavior.
• I have added/updated examples and tests for any new behavior.
• If this is a significant change, an issue has already been created where the problem / solution was discussed: [N/A, or add link to issue here]
  

PR Description

The LineChart fill draws using intervals to avoid
memory issues, but with a larger data set and many
different (darker) colors Android does not draw the
drawable all the way to the edge of the interval.
This makes it look like there are spaces between the fill.
Draw a little beyond the existing interval so there are no gaps.

Here is what it looks like before my change, look closely at the white vertical lines at ~1/5 ~3/5 ~4/5 of the way across the X-axis.

The same color with the fix no longer has gaps.

[hannesa2]

It's included here https://github.com/AppDevNext/MPAndroidChart/releases/tag/3.1.0.7

[giantramen]

@hannesa2 There's actually an issue with this when the fill color isn't fully opaque so you probably want to remove that.
Up for suggestions on how to fix this issue for the non-opaque cases, for my use case, we can guard around it at the client-side.

[hannesa2]

so you probably want to remove that.

What should I do ? If it's related to my fork, then let's continue there

[Paget96]

I really like this library and using it in my apps, I would like to call people to continue with this awesome thing. I have forked the repo and started working on it! So I am ready as well to accept pull requests, I'll notify other people from here as well!
Would be more than happy if we continue with this awesome project.

Code is full kotlin now!

Make your pull requests here:
https://github.com/Paget96/MPAndroidChart