Bumps version to 0.32a1

[ci skip]
scraper.py: Checks None before parse_refresh().

Closes chfoo/wpull#112
processor.py: Ignores document decode errors during scraping.

Closes chfoo/wpull#113
document.py: Lowers detect_response_encoding peek default to 128KB.

1MB can sufficently cause Wpull to hang for too long.
app.py: Sets the highest min logger level possible instead of debug.

Reduce string formatting calls when --debug is not enabled.
url.py: Simplifies if cases for is_percent_encoded() and split_query()
document.py: Abstracts doc type detection into BaseDocumentDetector.
document.py: Adds XMLDetector and detector unit tests.
converter,document: Adds XML, XHTML detection. Supports XHTML doc conversion.
scraper.HTMLScraper: Scrapes links from link,url,icon element text.
changelog: Updates latest to 0.32.
Bumps version to 0.32.

Merge commit 'd07172c0be2f910d9d95fddb487a4917aab73c70'

Conflicts:
	wpull/version.py