Add a C-source spell-checking facility. make misspell (on Nix)

FossilOrigin-Name: 26c1bb4bd9e9f56613c3aa87407a7f562fd4ebde5bfd6dece02078001d9a45f8

src/mutex_w32.c

@@ -38,7 +38,7 @@ struct sqlite3_mutex {
   CRITICAL_SECTION mutex;    /* Mutex controlling the lock */
   int id;                    /* Mutex type */
 #ifdef SQLITE_DEBUG
-  volatile int nRef;         /* Number of enterances */
+  volatile int nRef;         /* Number of entrances */
   volatile DWORD owner;      /* Thread holding this mutex */
   volatile LONG trace;       /* True to trace changes */
 #endif