Fix bug where "Sprite doesn't exist" error message was being truncated.
James Byrne authored
Detail:
  cache_sprite_doesnt_exist_error routine in MsgCode failed to take into
  account the fact that the messages file might be tokenised. Calling
  MessageTrans_Lookup with R2=0 gives you the length of the unexpanded
  message in R3. Now fixed to work in a better way.
  Also rename fp to r11 in swiv2 file to avoid assembler warnings.
Admin:
  Soft-loaded module tested. Problem seems to be solved.


Version 1.17. Tagged as 'SprExtend-1_17'
72e3ff6f