Feature: #183 custom window shader & #193 --no-fading-destroyed-argb

- Add --glx-fshader-win, which specifies a custom fragment shader for
  painting windows. compton-default-fshader-win.glsl is the shader with
  default behavior, and compton-fake-transparency-fshader-win.glsl
  provides a template of fake transparency. (#183)

- Add --force-win-blend to force all windows to be painted with
  blending.

- Add --no-fading-destroyed-argb, as a workaround of bugs in some WMs.
  (#193)

compton.sample.conf

@@ -48,6 +48,7 @@ fading = true;
 fade-in-step = 0.03;
 fade-out-step = 0.03;
 # no-fading-openclose = true;
+# no-fading-destroyed-argb = true;
 fade-exclude = [ ];
 
 # Other
@@ -84,5 +85,5 @@ glx-swap-method = "undefined";
 # Window type settings
 wintypes:
 {
-  tooltip = { fade = true; shadow = false; opacity = 0.75; focus = true; };
+  tooltip = { fade = true; shadow = true; opacity = 0.75; focus = true; };
 };