allow non-16x16 rooms

src/room.rs

@@ -110,7 +110,7 @@ impl From<String> for Room {
         }
 
         let lines = &lines[1..];
-
+        let dimension = lines.len(); // x or y, e.g. `16` for 16x16
         let mut tiles: Vec<String> = Vec::new();
 
         for line in lines.into_iter() {
@@ -120,7 +120,7 @@ impl From<String> for Room {
                 .collect();
 
             if ! comma_separated { line = line[1..].to_owned(); }
-            let line = line[..16].to_owned();
+            let line = line[..dimension].to_owned();
 
             for tile_id in line {
                 tiles.push(tile_id.to_string());