Improve code quality

[jogboms]

Fixes #60
Fixes #57

[jogboms]

@aagarwal1012 This is how far I can go for now, what do you think?

[aagarwal1012]

@jogboms, changes look really good. Awesome work!

[aagarwal1012]

This time don't make a Squash Merge.

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@636d940). Click here to learn what that means.
The diff coverage is 99.74%.

@@            Coverage Diff            @@
##             master      #59   +/-   ##
=========================================
  Coverage          ?   98.76%           
=========================================
  Files             ?       24           
  Lines             ?      890           
  Branches          ?        0           
=========================================
  Hits              ?      879           
  Misses            ?       11           
  Partials          ?        0

Impacted Files	Coverage Δ
lib/src/spinning_circle.dart	100% <100%> (ø)
lib/src/hour_glass.dart	100% <100%> (ø)
lib/src/three_bounce.dart	100% <100%> (ø)
lib/src/rotating_plain.dart	100% <100%> (ø)
lib/src/folding_cube.dart	100% <100%> (ø)
lib/src/ripple.dart	100% <100%> (ø)
lib/src/circle.dart	100% <100%> (ø)
lib/src/rotating_circle.dart	100% <100%> (ø)
lib/src/pulse.dart	100% <100%> (ø)
lib/src/fading_grid.dart	100% <100%> (ø)
... and 14 more

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