Implement download status handling on Fremantle

This allows users to cancel/pause/resume and clean up
downloads in the downloads list and manage downloads on
a per-episode basis in the episode dialog.
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch fremantle
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#	modified:   data/ui/gpodderstackableepisode.ui
#	modified:   data/ui/gpodderwelcome.ui
#	modified:   src/gpodder/gui.py
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#	0001-Support-stackable-window-for-episode-shownotes-dialo.patch
#	0002-Implement-downloads-as-stacked-window-remove-toolba.patch
#	0003-Remove-unnecessary-code-parts-for-Fremantle.patch
#	0004-Hildonize-widgets-in-the-preferences-dialog.patch
#	0005-Hildonization-for-confirmation-and-information-dialo.patch
#	core
#	src/gpodder/__init__.pyc
#	src/gpodder/config.pyc
#	src/gpodder/console.pyc
#	src/gpodder/corestats.pyc
#	src/gpodder/dbsqlite.pyc
#	src/gpodder/download.pyc
#	src/gpodder/draw.pyc
#	src/gpodder/dumbshelve.pyc
#	src/gpodder/feedcore.pyc
#	src/gpodder/gui.pyc
#	src/gpodder/libconverter.pyc
#	src/gpodder/libgpodder.pyc
#	src/gpodder/liblogger.pyc
#	src/gpodder/libpodcasts.pyc
#	src/gpodder/libtagupdate.pyc
#	src/gpodder/maemo.pyc
#	src/gpodder/my.pyc
#	src/gpodder/opml.pyc
#	src/gpodder/resolver.pyc
#	src/gpodder/services.pyc
#	src/gpodder/sync.pyc
#	src/gpodder/uibase.pyc
#	src/gpodder/util.pyc
#	src/gpodder/widgets.pyc
