preventCurveOverShooting sounds like mitigation rather than solution

Hey, amazing plugin, please don't get me wrong with this issue.

There are a lot of [issues](https://github.com/imaNNeo/fl_chart/issues?q=is%3Aissue+preventCurveOverShooting+) that include the keyword `preventCurveOverShooting`. It is always suggested to the problem that can be seen on the picture (taken from one of the issues):

But I don't think it is a solution. While it's nice to have a control over "roundness", there shouldn't be `preventCurveOverShooting+preventCurveOvershootingThreshold` as there shouldn't be any over shooting in the first place. Chart shouldn't display data that doesn't exist.

Those bumps are buggy and glitchy. `aboveBarData` and `belowBarData` doesn't colour them when they are rendered beyond bounds. The issue https://github.com/imaNNeo/fl_chart/issues/25 has been closed, despite glitch reported there by @jamesblasco - line has inconsistent thickness when those `prevent...` are toggled on.

Once again, amazing work, love your plugin, but would kindly appreciate reconsidering this implementation. We just want round lines, not zigzags :)

Start by reviewing the line-chart curve behavior around preventCurveOverShooting and preventCurveOvershootingThreshold, including the earlier discussion in issue #25. Compare the rendering of aboveBarData and belowBarData and the reported line-thickness inconsistency. Done means round lines no longer overshoot the supplied data or produce the described coloring and thickness glitches.

Written by the indexing model from the issue text.