[1/2] explorer: implement the explorer using IExplorerBrowser

[Juan Lang]

Hi Jay,

+static void MakeExplorerWindow(IShellFolder* startFolder, HINSTANCE hInstance)

I know the general rule of thumb when modifying an existing file is to
keep its style, but we also tend to stay away from this style of
function naming.  It looks too much like the functions could be Win32
API names.  Preferred style is the "one true style" of function
naming, e.g. make_explorer_window instead.  As it happens, explorer.c
is the odd man out in programs/explorer, and since it only has 4
functions at the moment, it's probably better to change them than to
add more functions with this style.

Thanks,
--Juan