Improve the imfilter() function to do kernel filter separation.

[joa-quim]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.66667% with 2 lines in your changes missing coverage. Please review.

Project coverage is 85.96%. Comparing base (1c4f83f) to head (a7e74e9).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/lepto_funs.jl	91.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1649      +/-   ##
==========================================
+ Coverage   85.94%   85.96%   +0.02%     
==========================================
  Files         151      151              
  Lines       21222    21239      +17     
==========================================
+ Hits        18240    18259      +19     
+ Misses       2982     2980       -2     

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