Rtfcre

Plover relies on normalized steno strokes not having a number key if there are numbers in the stroke, and this was breaking compatibility between it and RTF files formatted for professional steno machines. This release normalizes steno notation.

This release adds support for the `\cxplvrortho` control word, which allows Plover to do orthographically-aware attachments. This is incompatible with previous behavior, in which *all* attachments were considered ortho-aware. Now `\cxplvrortho` has to be specified in order to be treated as ortho-aware.


{\*\cxs EURB}{\*\cxplvrortho}\cxds ish -> "EURB": "{^ish}",
{\*\cxs *EURB}\cxds ish -> "*EURB": "{^}ish",

This release fixes encoding issues when loading RTF files encoded in Windows-1252 (which, as I just learned, has always been the default encoding 🙃). Now `rtfcre` can properly read and write dictionaries with non-ASCII entries.