Remove deprecated code

[Baptouuuu]

Fix #68

[codecov]

Codecov Report

❌ Patch coverage is 99.30851% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.40%. Comparing base (a8aa1fb) to head (627e3f1).
⚠️ Report is 9 commits behind head on develop.

Files with missing lines	Patch %	Lines
proofs/application.php	96.80%	12 Missing ⚠️
tests/Set/CompositeTest.php	97.72%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop      #85      +/-   ##
=============================================
- Coverage      92.12%   91.40%   -0.73%     
+ Complexity      2080     1736     -344     
=============================================
  Files            177      162      -15     
  Lines          10377     9088    -1289     
=============================================
- Hits            9560     8307    -1253     
+ Misses           817      781      -36     

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