allow inlining (this did not provide a statistically significant performance boost - oh well)

src/tile.rs

@@ -10,10 +10,12 @@ pub struct Tile {
 }
 
 impl Tile {
+    #[inline]
     fn name_line(&self) -> String {
         optional_data_line("NAME", self.name.as_ref())
     }
 
+    #[inline]
     fn wall_line(&self) -> String {
         if self.wall.is_some() {
             format!("\nWAL {}", self.wall.unwrap())
@@ -22,6 +24,7 @@ impl Tile {
         }
     }
 
+    #[inline]
     fn colour_line(&self) -> String {
         if self.colour_id.is_some() {
             format!("\nCOL {}", self.colour_id.unwrap())