Update to MOI v1

[blegat]

Part of jump-dev/JuMP.jl#2564

Closes #30
Closes #31
Closes #32
Closes #33
Closes #34

[codecov]

Codecov Report

Merging #35 (9e025c4) into master (80b3a3f) will increase coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #35      +/-   ##
==========================================
+ Coverage   65.95%   66.02%   +0.06%     
==========================================
  Files          22       22              
  Lines        1460     1460              
==========================================
+ Hits          963      964       +1     
+ Misses        497      496       -1     

Impacted Files	Coverage Δ
src/variables.jl	76.69% <0.00%> (+0.42%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 80b3a3f...9e025c4. Read the comment docs.