Trivial GAF List Bindings

[mt-xing]

Introduces new Python bindings to the flatgfa-py project that allows one to trivially turn a GAF parse into a Python list of list of PyChunkEvent objects, which can then be iterated over.

Sample code:

graph = flatgfa.load("test.flatgfa")
print(graph.size)

for read in graph.test_gaf("test.gaf"):
    for event in read:
        print(event.handle)
        print(event.range)
        print(event.get_seq())

Note that handle, range, and get_seq() all return strings for now.