[Issue-100] handle single negative value auto range

[hkang1]

In the case of a scale with only one single value, the min / max values are going to be the same. NiceScale attempts to auto determine a reasonable range. Currently it only handles when the single value is a positive value (> 0).

• add support for the case when the single value is 0
• add support for the case when the single value is less than 0

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[codecov]

Codecov Report

Merging #101 (7645e7d) into main (0d6e7a2) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #101      +/-   ##
==========================================
+ Coverage   97.97%   97.99%   +0.01%     
==========================================
  Files          17       17              
  Lines        1534     1543       +9     
  Branches      516      519       +3     
==========================================
+ Hits         1503     1512       +9     
  Misses         31       31              

Impacted Files	Coverage Δ
src/classes/NiceScale.ts	100.00% <100.00%> (ø)

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