Context manager to override call-time settings?

[tmontes]

Idea from #35.

When completing several calls with the same call-time override settings instead of:

w(returns=<bool>, ignore_failures=<bool>).first_callable()
w(returns=<bool>, ignore_failures=<bool>).second_callable()

We go for a context manager as in:

with w(returns=<bool>, ignore_failures=<bool>) as w:
    w.first_callable()
    w.second_callable()

PS: Not sure if the proposed w rebinding in the with statement is achievable/desirable. Maybe.

[tmontes]

Thought:

• Chained-contexts probably need to be taken into account.

Example:

with w(returns=True, ignore_failures=True) as w1:
    w1.first_callable()
    w1.second_callable()
    with w1(ignore_failures=False) as w2:
        w2.third_callable()
        w2.fourth_callable()
    w1.fifth_callable()
    w1.sixth_callable()

Implementation will need to track a context settings stack like structure.