Replace filename const by sanitise() function

src/solvers/cafeteria.rs

@@ -8,7 +8,6 @@ pub struct Cafeteria {}
 impl Solver for Cafeteria {
     const PUZZLE_INDEX: u8 = 5;
     const PUZZLE_NAME: &'static str = "Cafeteria";
-    const INPUT_FILENAME: &'static str = "cafeteria.txt";
 
     fn process_data<R: BufRead>(&self, mut reader: R) -> (u64, u64) {
         // Builds intervals collection.

src/solvers/printing_department.rs

@@ -7,7 +7,6 @@ pub struct PrintingDepartment {}
 impl Solver for PrintingDepartment {
     const PUZZLE_INDEX: u8 = 4;
     const PUZZLE_NAME: &'static str = "Printing Department";
-    const INPUT_FILENAME: &'static str = "printing_department.txt";
 
     fn process_data<R: BufRead>(&self, reader: R) -> (u64, u64) {
         let mut grid = Grid::new(0, 0);

src/solvers/trash_compactor.rs

@@ -7,7 +7,6 @@ pub struct TrashCompactor {}
 impl Solver for TrashCompactor {
     const PUZZLE_INDEX: u8 = 6;
     const PUZZLE_NAME: &'static str = "Trash Compactor";
-    const INPUT_FILENAME: &'static str = "trash_compactor.txt";
 
     fn process_data<R: BufRead>(&self, reader: R) -> (u64, u64) {
         let mut part1 = 0;