Fix decoding of scientific notation

[morris-kelly]

Before submitting your PR, please confirm the following.

• [x] Describe the purpose for which you created this PR.
  Fix #458 as well as similar issues with scientific notation int and uint values.
• [x] Create test code that corresponds to the modification Test code has been added to the encoder to ensure that scientific notation is encoded properly, as well as TestDecoder_ScientificNotation. The scientific notation test could be moved to be part of the large TestDecoder.

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 78.72%. Comparing base (b2a8cc6) to head (e9430c0).

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #463 +/- ## ========================================== + Coverage 78.65% 78.72% +0.06% ========================================== Files 13 13 Lines 3983 4004 +21 ========================================== + Hits 3133 3152 +19 - Misses 590 592 +2 Partials 260 260 ```