Correct spelling or grammatical mistakes in various comments

src/fileio.c

@@ -406,7 +406,7 @@ bool load_game (int num)
 	lineno++;
     }
 
-    // Read in a dummy sentinal value
+    // Read in a dummy sentinel value
     load_game_read_int(n, n == GAME_FILE_SENTINEL);
 
     if (fclose(file) == EOF) {
@@ -587,7 +587,7 @@ bool save_game (int num)
 	fprintf(file, "%s", encbuf);
     }
 
-    // Write out a dummy sentinal value
+    // Write out a dummy sentinel value
     save_game_write_int(GAME_FILE_SENTINEL);
 
     if (fclose(file) == EOF) {

src/move.h

@@ -57,7 +57,7 @@ extern void select_moves (void);
   This function displays the galaxy map and the current moves, then waits
   for the player to select one of the moves.  On entry, current_player
   contains the current player number; quit_selected and/or abort_game may
-  be true (if so, get_move() justs returns SEL_QUIT without waiting for
+  be true (if so, get_move() just returns SEL_QUIT without waiting for
   the player to select a move).  The return value is the choice made by
   the player.
 

src/utils.c

@@ -202,7 +202,7 @@ static bool add_currency_symbol = false;	// Do we need to add "$"?
   Returns:    (nothing)
 
   This function copies n bytes from *src into *dest, applying a XOR with
-  the contents of xor_table in the process.  It is a reversable function:
+  the contents of xor_table in the process.  It is a reversible function:
   apply_xor(apply_xor(buffer)) == buffer.  It is used by both scramble()
   and unscramble().
 */
@@ -743,7 +743,7 @@ char *unscramble (char *restrict dest, const char *restrict src,
 	    return NULL;
 	}
 
-	// Descramble xorbuf using *key, ignoring CRC32 in front
+	// Unscramble xorbuf using *key, ignoring CRC32 in front
 	apply_xor(dest, midxor, xorlen - SCRAMBLE_CRC_LEN, key);
 
 	// Convert the output to a C string

src/utils.h

@@ -87,9 +87,9 @@ extern void init_program_name (const char *argv0);
   Returns:    const char *   - Pointer to home directory
 
   This function returns the full pathname to the user's home directory,
-  using the HOME environment variable.  Note that the existance or
+  using the HOME environment variable.  Note that the existence of or
-  writability of this pathname is NOT checked by this function.  NULL is
+  ability to write to this pathname is NOT checked by this function.
-  returned if the home directory cannot be determined.
+  NULL is returned if the home directory cannot be determined.
 */
 extern const char *home_directory (void);
 
@@ -102,8 +102,9 @@ extern const char *home_directory (void);
   This function returns the full pathname to a potentially-writable
   subdirectory within the user's home directory.  Essentially, this
   function returns home_directory() + "/."  + program_name.  Note that
-  this path is NOT created by this function, nor is the writability of
+  this path is NOT created by this function, nor is the ability to write
-  this path checked.  NULL is returned if this path cannot be determined.
+  to this path checked.  NULL is returned if this path cannot be
+  determined.
 */
 extern const char *data_directory (void);