testing/badapp.py: Allows path with queries.
engine.py: Adds URLItem.child_url_record()
processor,hook: Renames _should_fetch. Checks filters before inserting.

Re: chfoo/wpull#70
Implements --quota. Closes chfoo/wpull#3.
Implements --warc-max-size.

util.py: Adds truncate_file().

Re: chfoo/wpull#26
terse_options.rst: Updates for quota, warc-max-size, restrict-file-names.
Merge branch 'issue/70-many-links-hang' into develop
changelog.rst: Adds point about not adding URL to database if skipping.