Android XML: Filter does not honor Android escaping rules

[Chase Tingley]

For reference: https://developer.android.com/guide/topics/resources/string-resource#FormattingAndStyling

Android XML has an additional, non-XML layer of escaping applied, because apparently the text values are swapped directly into Java code without additional processing by the framework. (This seems like bad design to me, but what can you do.)

We neither honor this slash-escaping on import (we import \' as \' rather than ') or on export (we export ' as ' rather than \'). This applies to single and double quotes, @, and ?. Note that entity escaping for is also allowed, per the docs.