As per #810 & #796, only LUA_OPTIMIZE_MEMORY=2 & MIN_OPT_LEVEL=2 are
supported when building. This commit effects that limitation.
With this change modules/auxmods.h no longer needs to be updated for
every new module, nor do module writers need to cater for a hypothetical
LUA_OPTIMIZE_MEMORY < 2 scenario.
With the new SDK soft-wdt it is no longer sufficient to tickle the hardware
watchdog, so all (found) instances have been changed to system_soft_wdt_feed().