Fix bugs and make improvements to redbean

- Abort if .init.lua fails
- Refactor redbean to use new append library
- Use first certificate if SNI routing fails
- Use function/data sections when building Lua
- Don't use self-signed auto-generated cert for client
- Add -D staging dirs to redbean lua module default path

libc/stdio/appendz.c

@@ -25,6 +25,9 @@
 
 /**
  * Returns size of append buffer.
+ *
+ * @return i is number of bytes stored in buffer
+ * @return n is number of bytes in allocation
  */
 struct appendz appendz(char *p) {
   struct appendz z;