Fix: Some code and comment typos

Found with codespell

src/tgp.cpp

@@ -47,7 +47,7 @@
  * second sets the major variations to that, ... until finally the smallest
  * bumps are added.
  *
- * Usefully, this routine is totally scaleable; so when 32bpp comes along, the
+ * Usefully, this routine is totally scalable; so when 32bpp comes along, the
  * terrain can be as bumpy as you like! It is also infinitely expandable; a
  * single random seed terrain continues in X & Y as far as you care to
  * calculate. In theory, we could use just one seed value, but randomly select
@@ -262,7 +262,7 @@ static amplitude_t GetAmplitude(int frequency)
 	 * areas with a particular gradient so that we are able to create maps without too
 	 * many steep slopes up to the wanted height level. It's definitely not perfect since
 	 * it will bring larger rectangles with similar slopes which makes the rectangular
-	 * behaviour of TGP more noticable. However, these height differentiations cannot
+	 * behaviour of TGP more noticeable. However, these height differentiations cannot
 	 * happen over much smaller areas; we basically double the "range" to give a similar
 	 * slope for every doubling of map height.
 	 */
@@ -977,7 +977,7 @@ static void TgenSetTileHeight(TileIndex tile, int height)
  * The main new land generator using Perlin noise. Desert landscape is handled
  * different to all others to give a desert valley between two high mountains.
  * Clearly if a low height terrain (flat/very flat) is chosen, then the tropic
- * areas wont be high enough, and there will be very little tropic on the map.
+ * areas won't be high enough, and there will be very little tropic on the map.
  * Thus Tropic works best on Hilly or Mountainous.
  */
 void GenerateTerrainPerlin()