Merge pull request #39 from akustik/master

Implemented P31 to P33
Solves P31 (naive impl)
Solves P32
Solves P33
Code cleanup
Merge pull request #40 from ignasi35/master

Arithmetics P31-P33
Solve P21... old homework :-(
Solve P22 and P23. Old homework :-(
Solve P24. Old homework :-(
Merge pull request #41 from ignasi35/master

P21 to P24
P34
P35
remove private
P36
Merge pull request #42 from padilo/arithmetic_week2

Arithmetic week2
Added plugin for sublime text. Problems up to p38