Wedge load noise

[teubert]

Add "wedge noise" - that is, noise that increases the further we are in the future.

This is an important feature as it allows us to represent how our uncertainty in the future load increases the further out we are.

Also, renamed GaussianNoiseLoadWrapper to GaussianNoiseWrapper for conciseness. It's still in the loading sub package (progpy.loading.GaussianNoiseWrapper) so "Load" wasn't necessary. I leave an alias for backwards compatibility, but the documentation and examples will use GaussianNoiseWrapper.

Closes #84

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[codecov-commenter]

Codecov Report

Merging #97 (1057c3c) into dev (0c23145) will decrease coverage by 0.03%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##              dev      #97      +/-   ##
==========================================
- Coverage   84.22%   84.19%   -0.03%     
==========================================
  Files          99       99              
  Lines       10179    10183       +4     
==========================================
+ Hits         8573     8574       +1     
- Misses       1606     1609       +3     

Files Changed	Coverage Δ
src/progpy/loading/gaussian_wrapper.py	37.50% <42.85%> (-4.17%)	⬇️
src/progpy/loading/__init__.py	100.00% <100.00%> (ø)