initial code drop

impala is intended to be an implementation of the Python_
PEP302_ protocol (`sys.meta_path` hook for the `import` statement)
allowing the user to import packages and modules from arbitrarily
named directories and files.

the packaging part (`make dist`) is completely untested.

.. _Python: http://www.python.org/
.. _PEP302: http://www.python.org/dev/peps/pep-0302/

* Python 2.7 has bug_, `import foo` within packages and submodules
  is supposed to be "absolute", but it's relative, and ::

    from __future__ import absolute_import

  is in fact still necessary.

  .. _bug: http://stackoverflow.com/a/11741846/209605

  impact:

  let's have an impala'd package `pkg` in `/somedir`.
  then `import sys` in `/somedir/__init__.py` will call
  `impala.Finder.find_package('pkg.sys', ['/somedir'])`.

* looks like i could get rid of Loader.path_to and just
  use ldr.fspath directly... but maybe i'll want to
  have Loader instances handle multiple packages/modules,
  and the flexibility could come in handy.  yeah, YAGNI.

* the tests report only the first failure from each .t file;
  the rest is usually snowballing fallout.
impala-0.1

seems to be good enough to let me develop `pyg`_.
let's see how high it can jump in the wild.

.. _pyg: https://github.com/roman-neuhauser/pyg
VERSION is 0.1.99 now