auto merge of #10891 : chris-morgan/rust/macroize-(or-should-that-be-macroify)-syntax--parse--token-so-that-we-don't-make-mistakes-and-to-reduce-the-maintenance-burden, r=huonw

I also renumbered things at the same time; ``in`` was shifted into its
alphabetical position and the reserved keywords were reordered (a couple
of them were out of order).

Unused special identifiers are also removed in the second part.

Author: bors