Haiku-Depot: Initial skeleton application
HaikuDepot: BGroupView for the controls defining list contents
HaikuDepot: PackagesListView

BColumnListView derived class with code-duplication from
DriveSetup that should be refactored eventually (BIconStringColumn
and BColumn implementation to show it). Does nothing except create
some columns.
HaikuDepot: BGroupView holding buttons for package actions...

... that can be applied to the selected package(s). Does nothing
except create the buttons and layout.
HaikuDepot: Added new classes to build and main window.
HaikuDepot: BTabView with About, Rating & comments and Changelog

Completely non-functional. Should be replaced by something visually
more unified. The selected package's title and icon should be always
visible above the three sections, and the sections should not be
tabs but something more subtle.
HaikuDepot: Added PackageInfoView, moved buttons to bottom
HaikuDepot: Populate menu fields (non-functional)
HaikuDepot: "Show" is better than "Category" for what it does.
Revert "Introduce vnode op supports_operation(), fix devfs_io()"

This reverts commit 98a5231fe5497c526849f2d84b1a9bbcbdfd2dbc.