[BlenderBIM] Interface strings should be i18n

[globalcitizen]

Strings should be internationalized.

Blender's notes on internationalization has specific notes on translating unofficial addons.

[Moult]

This is a valid bug, but a very low priority, considering that UI changes are very frequent right now.

If you'd like to translate a few of the more stable parts of the UI, go for it. Once you've done a small example, this can be labeled a good first issue for future contributors.

[Moult]

A year later, and the UI is still changing too frequently for this bug to be considered a high priority.

[Moult]

Just a bump that i18n is starting to be considered in #1646.