graph reweaving

[mmolari]

graph reweaving

I added functions and tests for graph reweaving. Everything is contained in the reweave folder.

• classes.py contains the definition of all of the classes.
• utils.py, slice_utils.py and interval_utils.py contain the reweave function and all of the utility functions needed.
• test_slice.py, test_intervals.py and tests.py contain 19 different tests.
• merge.py contains one additional function to solve promises and merge blocks, that can be integrated and tested later, but in the meantime is sketched here.

Since the code and the tests are complex at times I also added some notes with a more verbose description of the classes and their attribute, the functions and the tests.