Some property labels need a context to disambiguate them from others
which have the same name.
The only way to show the proper text currently for such properties is
to override it in the UI code with a translation context, like:
```python
layout.prop(obj, "area", text="Area",
context=i18n_contexts.amount)
```
Python properties already store a translation context though, but this
context cannot be chosen from a Python script.
For instance, typing:
```python
bpy.types.Scene.test_area = bpy.props.BoolProperty(name="Area")
print(bpy.context.scene.bl_rna.properties['test_area'].translation_context)
```
will print `*`, the default context for Python props.
This commit allows specifying a context in this manner:
```python
from bpy.app.translations import contexts as i18n_contexts
bpy.types.Scene.test_number_area = bpy.props.BoolProperty(
name="Area", translation_context=i18n_contexts.amount
)
print(bpy.context.scene.bl_rna.properties['test_number_area'].translation_context)
```
will now print `Amount` and can be translated differently from other
labels. In this instance, the word for a surface area measurement,
instead of a UI area.
This change is aimed at Python developers who want to translate their
add-ons, rather than end-users. For this reason, the context is not
exposed in the property editing UI.
Damien Picard