Fixing depracation warning: time.clock(); collections.Iterable

[tomasprinda]

Changed if isinstance(module, collections.Iterable) to if isinstance(module, collections.abc.Iterable). From doc abc was added in python 3.3, so it might not work on earlier versions. Is it problem for somebody?

Changed time.clock() to timeit.default_timer()

closes #27

[tomasprinda]

Failing in python 3.4. :(

What do you think about this solution? It should be even more reliable.
https://stackoverflow.com/a/1952655/6579599

[tomasprinda]

And thanks to @tivvit for Travis CI testing. Now I see it is very useful. ;-)

[alaneckhardt]

I looked where this is used - chain_repr nor chain_mtime are not crucial, they're for user info only.
I would be fine with ducktyping approach using try except. The check is there only so that the following for module in chain: succeeds.

[tirkarthi]

time.clock is now removed in 3.8 : python/cpython#13270