Fix graph height calculation for small value ranges

[guptarohit]

This merge request addresses an issue where graphs with small value ranges (less than 1) were not being displayed correctly, often resulting in a flat line at 0.00. This will resolve the issue #56.

The problem was caused by the height calculation rounding down to 0 for small intervals, which led to division by zero errors in subsequent calculations. This was also suggested by @palash25 in the comments of the issue, thanks.

Changes made to resolve the issue:

• Refactored the height calculation logic into a separate function calculateHeight().
• Implemented a scaling mechanism for small intervals, i.e. when the difference in max & min values of series is <1

The solution maintains consistency in height calculation across different scales of data, so graphs with ranges like {0.2, 0.3, 0.1} will have a similar appearance to graphs with ranges like {2, 3, 1}.

Also, refactored a bit related to the conflicting name of variables with built-in methods.

[coveralls]

Pull Request Test Coverage Report for Build 11530060756

Details

• 17 of 17 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.08%) to 96.063%

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Totals
Change from base Build 10341981841:	0.08%
Covered Lines:	366
Relevant Lines:	381

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💛 - Coveralls