Change version format to comply with PEP440.
Misc: Update @version to match the new version format.
src/conf.py: Remove unicode characters from the source code.
Add optional dependencies introduced in Limnoria in INSTALL.md.
Fix links in INSTALL.md.
Fix errors detected by PyLint.
Channel: Add command @ban hostmask.
i18n: Prevent untranslated strings from having empty translations
Debug: Fix Python 3 compatibility. Closes GH-565.
Plugin: Remove duplicate !list command

It also exists in Misc.
Remove test case for !plugin list
Merge pull request #567 from nyuszika7h/plugin-remove-list

Plugin: Remove duplicate !list command