Interface language setting and change: default (English) and alternatives

[aarppe]

As the language of the dictionary interface (the language used in the various buttons and panes, which have been stored in the messages.po files per each language):

1. English should be the default interface language; and

2. As alternatives, one should be able to change with some toggle/button English to 2a. Cree/SRO-circumflex or 2b. Cree/SRO-macron or 2c. Cree/syllabics.

In principle, choosing the interface language should also be reflected in which of the various paradigm layouts will be presented by default (one could even consider hiding the others).

This may lead to an associated technical issue concerning where the various interface language translations will be stored (i.e. the message.po files) and how they are specified an structured, and how in the the case of Cree, the Cree translations are represented in either flavor of SRO or syllabics.