message: Don't compile with -fpermissive.
  I...guess I understand why this is on by default.  Do not want.
diff: @@ -25,7 +25,9 @@ lib_extra_dirs =
  ; I hit some build errors, they didn't look too bad but with gnu++17
  ; they aren't there at all.
  build_flags = -Icommon/include/ -std=gnu++17 -Wall -Werror
  -build_unflags = -std=gnu++11
  +build_unflags =
  + -std=gnu++11
  + -fpermissive
  [env:uno]
  platform = atmelavr
  