Option to update imports with changes in the imported file

A new feature for importing (File > Import) such that a user may choose to 
"link" the imported geometry, etc, to the imported file. Changes to the 
imported file could then be reflected in the drawing (e.g. through something 
like File > Refresh Linked Imports)

Some humble thoughts on how this might work:
- .heeks file format would need to be able to model this
- maybe imported items from a single file could not be separated and 
manipulated individually (as they can be now) when they are linked to another 
file, only transforms on the entire import should be allowed, so some sort of 
locking functionality for the imported geometry would be required
- the imported file location should be stored as a relative path, if possible, 
to accommodate workspace directories
- if the imported file resides on a distant share or drive, an absolute path 
should be supported to accommodate shared model reuse.

Possible use case:
1. The user produces a model of a reusable component, saves the component as 
X:\Products\Reusable\Standard Wheel.heeks.
2. The user starts a new file, does some modelling, and wishes to use Component 
X in the current file. The user selects File > Import and Link, navigates to 
X:\Products\Reusable, selects Standard Wheel.heeks and the component appears in 
the drawing.
3. The user selects the component. The properties pane shows an additional 
property, "Linked to," value, "X:\Products\Reusable\Standard Wheel.heeks"
4. The user makes 3 copies of the original import, performs rotations and 
movement transforms on the instances to arrange them in the drawing, etc.
5. The user opens Standard Wheel.heeks, makes some changes, and saves the file.
6. In the file created in step 2, the user selects File > Refresh Linked 
Imports. The changes from Standard Wheel.heeks appear in the drawing at all 
four instances, with the previous transforms still applied to the four.
7. The user saves the new drawing at X:\Products\Toys\Car.heeks
8. The user clicks an instance of the imported component from step 4. The 
properties pane shows the property, "Linked to," with value, 
"..\Reusable\Standard Wheel.heeks"
Original issue reported on code.google.com by jason.st...@gmail.com on 21 Feb 2011 at 6:44
elliotf / heekscad

Option to update imports with changes in the imported file #333
