Improvement: --blur-background-exclude #98 & MESA_swap_control & others

- Add --blur-background-exclude. (#98)

- Add `opengl-mswc` VSync, which uses MESA_swap_control instead of
  SGI_swap_control. I don't expect it to perform better than
  SGI_swap_control, though.

- Update CMakeLists.txt .

- Add a few targets for D-Bus `win_get`. Misc changes.

- Known issue: Apparently I've forgotten implementing --inactive-dim on
  GLX backend... Silly me.

src/compton.h

@@ -667,6 +667,12 @@ win_update_prop_shadow(session_t *ps, win *w);
 static void
 win_determine_shadow(session_t *ps, win *w);
 
+static void
+win_determine_invert_color(session_t *ps, win *w);
+
+static void
+win_determine_blur_background(session_t *ps, win *w);
+
 static void
 win_on_wtype_change(session_t *ps, win *w);
 
@@ -988,6 +994,9 @@ vsync_opengl_oml_init(session_t *ps);
 static bool
 vsync_opengl_swc_init(session_t *ps);
 
+static bool
+vsync_opengl_mswc_init(session_t *ps);
+
 #ifdef CONFIG_VSYNC_OPENGL
 static int
 vsync_opengl_wait(session_t *ps);