Fixes #79 -- lots of PEP-8 violations.

Note that the Sphynx-generated Python file does not pass. Since it's
auto-generated by sphynx, we'll need to add an exception in the PR for
MUCH faster `last` for non-sequences by using a deque
Fixed bug in the accumulate function
Add jackknife function (see #66) in the sandbox module (see #67)

jackknife: repeatedly iterate over seq, each time omitting a successive element

This is the first addition to the sandbox.   The purpose and usage of the
sandbox still needs to be documented.

The goal for `jackknife` is to eventually be in a `sampling` module, which
may end up being a separate project.
Document `jackknife` return type and offer recipe for changing it
Merge pull request #83 from eigenhombre/pep8-fix

Fixes #79 -- lots of PEP-8 violations.
`get` is faster for list of indices with no default

PR #57 put an emphasis on the performance of `get` because it is
so frequently used.  Some timings for `get` were given in that thread.
This commit improves those benchmarks as follows:

"test list" is 50% faster (using a two-element list of indices).
"test long list" is 100% faster (using a 100-element list of indices).

This is achieved because `operator.itemgetter(*ind)(seq)` is significantly
faster than `tuple(seq[i] for i in ind)`.  For me, it is 3x faster.
add test for accumulate on iterator

Provided by @jcrichton
separate accumulate on iterable test
Merge pull request #86 from eriknw/get_with_itemgetter

`get` is faster for list of indices with no default
Merge pull request #84 from eriknw/last_with_deque

MUCH faster `last` for non-sequences by using a deque
Merge pull request #85 from eriknw/jackknife_sandbox

Add jackknife function (see #66) in the sandbox module (see #67)
add tests for memoize with kwargs
memoize handles kwargs
only use kwargs in memoize if function has kwargs

Benchmark with bench/test_memoize.py
Before around 0.06s
After around 0.04s

Benchmark with bench/test_memoize_kwargs.py
Negligible increase if any (variance is oddly high)
memoize key on kwargs.items(), not kwargs
Merge branch 'master' into update_accumulate

Conflicts:
	toolz/itertoolz/tests/test_core.py
Merge pull request #87 from mrocklin/update_accumulate

Update accumulate
test memoize on curry
Merge pull request #63 from mrocklin/memoize-kwargs

Memoize kwargs