lua remove and consolidate some rb plugin functions

removes some usless / duplicated functions
removes atoi - lua tonumber() does this for you
removes strlen - lua string.len does this for you
removes system_memory_guard - if a device that actually implements
              system_memory_guard needs it we can add it back conditionally

consolidates talk_number and talk_spell (on backend)
consolidates talk_shutup and talk_force_shutup talk_shutup(bForce)

Change-Id: Id132642f087975a7c132e99a668a41c977942b81
2 files changed