Add per window type option full-shadow

When this option is enabled for a window type, shadow will be drawn in
areas that are obscure by the shape of the window.

Useful when the given window type has parts of the window transparent,
and you want to have shadows in those areas.

Fixes #45

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/common.h

@@ -531,6 +531,7 @@ typedef struct options_t {
   // === Shadow ===
   /// Enable/disable shadow for specific window types.
   bool wintype_shadow[NUM_WINTYPES];
+  bool wintype_full_shadow[NUM_WINTYPES];
   /// Red, green and blue tone of the shadow.
   double shadow_red, shadow_green, shadow_blue;
   int shadow_radius;