GitLab

Ultimately all static strings should be qstr.  This entry in the type
structure is only used for printing error messages (to tell the type of
the bad argument), and printing objects that don't supply a .print method.

Want common qstrs to be first in the list so they have the lowest ids,
so that in the byte code they take up the least room.

Also, add qstr's for string appearing in unix REPL loop, gross effect
being less allocations for each command run.

Can now have null bytes in strings.  Can define ROM qstrs per port using
qstrdefsport.h