Support proper %g, %f, and %a float formatting

See #61
See #104

examples/hello4.c

@@ -1,21 +0,0 @@
-#if 0
-/*─────────────────────────────────────────────────────────────────╗
-│ To the extent possible under law, Justine Tunney has waived      │
-│ all copyright and related or neighboring rights to this file,    │
-│ as it is written in the following disclaimers:                   │
-│   • http://unlicense.org/                                        │
-│   • http://creativecommons.org/publicdomain/zero/1.0/            │
-╚─────────────────────────────────────────────────────────────────*/
-#endif
-#include "libc/errno.h"
-#include "libc/stdio/stdio.h"
-
-int main(int argc, char *argv[]) {
-  printf("abcdefghijklmnopqrstuvwxyz "
-         "ABCDEFGHIJKLMNOPQRSTUVWXYZ "
-         "!@#$$%%^&*(){}%%* "
-         "0123456789 "
-         "%3d\n",
-         argc);
-  return errno;
-}