Add primal and dual tolerances in presolve

[mtanneau]

Closes #98

[codecov-commenter]

Codecov Report

Merging #100 (89bcc5c) into master (27fee90) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #100      +/-   ##
==========================================
+ Coverage   90.37%   90.38%   +0.01%     
==========================================
  Files          36       36              
  Lines        2555     2558       +3     
==========================================
+ Hits         2309     2312       +3     
  Misses        246      246              

Impacted Files	Coverage Δ
src/Presolve/Presolve.jl	93.94% <100.00%> (+0.01%)	⬆️
src/Presolve/empty_column.jl	100.00% <100.00%> (ø)
src/Presolve/empty_row.jl	100.00% <100.00%> (ø)
src/Tulip.jl	100.00% <100.00%> (ø)
src/model.jl	95.29% <100.00%> (ø)

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