cursor module done with one unsolved problem

1 bit cursor cannot be displayed normally

Conflicts:
	INSTALL
	Makefile.in
	aclocal.m4
	compile
	config.guess
	config.sub
	configure
	depcomp
	graph/local.mk
	install-sh
	ltmain.sh
	m4/libtool.m4
	missing
	utils/data_structures/external.h
	utils/data_structures/local.mk
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.
fix new cursor-drawing code

Now moving cursor won't leave shadow on screen, and warnings at compile
time are removed.

cursor_paint() function calls screen_flush to remove shadow, any callers
of this function don't need to flush screen for cursor anymore.

The next thing to do is to make the cursor's moving smoother. Currently
the cursor may disappear if moving too fast.

Conflicts:
	window_manager/window_manager_input_handler.c
speed up mouse moving

Converted default cursor into a smaller version(24x24). Together with
the change that reduces refreshes, new cursor can work almost smoothly
now.

One thing to remember is that cursor files can only have several fixed
sizes, namely 16x16, 24x24, 32x32, 48x48 etc. Sizes like 21x21 will
break the AND map, which specifies transparent area.

Next thing to do is to rearrange some code.

Conflicts:
	graph/graph_engine/engine_draw_cursor.c
cursor code clean up

engine_draw_cursor() doesn't actually need an extra argument which
specifies the drawing target, since cursor_gd now uses buffered access
mode, and the former function can simply draw on the buffer.

From the global point of view, however, the cursor still uses direct
access mode, because flushing is not needed.

Conflicts:
	graph/graph_engine/engine_draw_cursor.c
fix uninitialized variables
fix tab on repeated click on same head

Ignoring the set_focus message when the new focus is the same as the
current one.