* Added an abstraction for getting an BDataIO, DataSource and derived classes,
which allows to move I/O completely out of the GUI threads.
* Fleshed out application start, window creation, and file loading. We do now
create a window for every command line argument and load the referenced file
or, if none, create an empty window.
* Some improvements in the file loader. It does now correctly load the file,
but doesn't process the stored data yet.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30274 a95241bf-73f2-0310-859d-f6bbb57e9c96