`assert` keyword can be disabled by interpreter, so it's not reliable
for functional code.

A big spring clean of the docstrings (sure long time coming!)

 *  Fix typos,

 *  rewrite clumsy explanations,

 *  omit unnecessary and misleading parts,

 *  remove awkward and "smart" language,

 *  use consistent here-doc formatting across small and big docstrings
    (isolate quote mark triplets on own line.)

Not sure why but 2to3 suggested to enclose the % expression into
parentheses before passing it to print(); I did about the same thing
manually but a bit more readable.

module has been only used in one environment within one use case.  The
API is still not organized well (there might be some bad decisions),
documentation needs some reviewing, ant the name of the module is likely
to change in forseeable future.

Therefore it seems too brave to call it 1.0, I'd be happier if the above
was finished before that.

Also, I believe it's a good idea to adhere to Semantic Versioning model,
therefore 0.1.0.