Fillit

**hulamy and **vmanzoni

To do

Check if we have a file
Read file
Check if there are errors in file
- At least 1 tetrimino or less than 26
Check if every tetrimino is valid
- 4 char * 4 lines
- 4 blocks in 1 tetrimino
- No solo block
Transform file into tetriminos
Backtracking for smallest square
Transform tetriminos to letters
Print result
Optimisation