Fix projection of dw reformulation to original formulation

[guimarqu]

fix #252

Pure master variables was ignored...

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@39d9843). Click here to learn what that means.
The diff coverage is 83.33%.

@@            Coverage Diff            @@
##             master     #253   +/-   ##
=========================================
  Coverage          ?   83.45%           
=========================================
  Files             ?       49           
  Lines             ?     2926           
  Branches          ?        0           
=========================================
  Hits              ?     2442           
  Misses            ?      484           
  Partials          ?        0

Impacted Files	Coverage Δ
src/Coluna.jl	100% <ø> (ø)
src/MathProg/problem.jl	86.66% <50%> (ø)
src/MOIwrapper.jl	89.52% <90%> (ø)

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