add sliding_window_maxima

[nsajko]

Feature addition: add iterator whose elements are maxima of a sliding window over an original iterator.

[codecov]

Codecov Report

❌ Patch coverage is 98.64865% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 91.96%. Comparing base (568d12c) to head (b589762).
⚠️ Report is 14 commits behind head on master.

Files with missing lines	Patch %	Lines
src/IterTools.jl	98.64%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #126      +/-   ##
==========================================
+ Coverage   90.72%   91.96%   +1.23%     
==========================================
  Files           1        1              
  Lines         399      473      +74     
==========================================
+ Hits          362      435      +73     
- Misses         37       38       +1     

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[oxinabox]

why does this have some very aggressive compiler directives thoughout it?

these are going to require careful hand checking.
The compiler can normally work things out.

[nsajko]

bump

[nsajko]

bump

[oxinabox]

sorry, its just i am not sure if this belongs in this package or not.
It's a very intricate function.