Add cross, conv, cov, etc funs

[joa-quim]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 90.46243% with 33 lines in your changes missing coverage. Please review.

Project coverage is 85.86%. Comparing base (cf003f1) to head (90234de).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/signalcorr.jl	90.43%	33 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1680      +/-   ##
==========================================
+ Coverage   85.76%   85.86%   +0.09%     
==========================================
  Files         159      160       +1     
  Lines       22168    22513     +345     
==========================================
+ Hits        19013    19330     +317     
- Misses       3155     3183      +28     

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