- NLBConfig better error handling

- Implement payload so it attempts no processing of the image (I can now use it for ELF images!)
- Implement linux so it does what it has always done (but is now distinct from payload)
- Implement the new expr command so I can compute values (I got inspired)
- Micro fix to rom_fill_inbuf.c so we don't get back too many bytes (Thanks Ron)
- Fix for fallback_boot.c so it is always available.  Otherwise I can't say my boot succeeded.
- Added example config scripts for the p4dc6

src/include/part/fallback_boot.h

@@ -3,11 +3,7 @@
 
 #if !defined(ASSEMBLY)
 
-#if USE_FALLBACK_BOOT
 void boot_successful(void);
-#  else
-#    define boot_successful()
-#endif
 
 #endif /* ASSEMBLY */