removing auto-generated files

Forgot the configured header.
add resource files into distribution

Cursor icon files in resource/ will be installed into $pkgdatadir, and
window_manager/cursor.c now use a path given by automake to find default
cursor file.
allow finding cursor file in source tree

Before installation, the cursor files can't be found in specified
resource directory, and running server at this time causes crash.

Now we test if the installed files are available, and if not, use the
path in source tree.
Note: this method is problematic.