Add the ability to get/set the selected text.
**Calling the new methods:**
- `bpy.data.texts["Text"].region_as_string()`
- `bpy.data.texts["Text"].region_from_string("Replacement")`
Add the ability to get/set the selected text.
**Calling the new methods:**
- `bpy.data.texts["Text"].region_as_string()`
- `bpy.data.texts["Text"].region_from_string("Replacement")`