Import stylesheet code from hippo-canvas

Import:

  HippoCanvasTheme      => StTheme
  HippoCanvasThemeImage => StThemeImage
  HippoCanvasStyle      => StThemeNode

StThemeContext is a new class managing the theme for a stage and
global properties like resolution.

test-theme.c is a newly written test program to do verification of the
style matching and property handling rules.

Various changes are made in the import:

 - Comprehensive reindentation
 - guint32 pixels replaced with ClutterColor
 - General pseudo-class support added
 - Old-fashioned (non-bordered) background image support added, though
   with no support for repeat, etc.
 - Bug fixes for problems revealed by test program

https://bugzilla.gnome.org/show_bug.cgi?id=595990

src/st/st-theme-context.h

@@ -0,0 +1,50 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+#ifndef __ST_THEME_CONTEXT_H__
+#define __ST_THEME_CONTEXT_H__
+
+#include <clutter/clutter.h>
+#include <pango/pango.h>
+#include "st-theme-node.h"
+
+G_BEGIN_DECLS
+
+/**
+ * SECTION:StThemeContext
+ * @short_description: holds global information about a tree of styled objects
+ *
+ * #StThemeContext is responsible for managing information global to a tree of styled objects,
+ * such as the set of stylesheets or the default font. In normal usage, a #StThemeContext
+ * is bound to a #ClutterStage; a singleton #StThemeContext can be obtained for a #ClutterStage
+ * by using st_theme_context_get_for_stage().
+ */
+
+typedef struct _StThemeContextClass StThemeContextClass;
+
+#define ST_TYPE_THEME_CONTEXT             (st_theme_context_get_type ())
+#define ST_THEME_CONTEXT(object)          (G_TYPE_CHECK_INSTANCE_CAST ((object), ST_TYPE_THEME_CONTEXT, StThemeContext))
+#define ST_THEME_CONTEXT_CLASS(klass)     (G_TYPE_CHECK_CLASS_CAST ((klass), ST_TYPE_THEME_CONTEXT, StThemeContextClass))
+#define ST_IS_THEME_CONTEXT(object)       (G_TYPE_CHECK_INSTANCE_TYPE ((object), ST_TYPE_THEME_CONTEXT))
+#define ST_IS_THEME_CONTEXT_CLASS(klass)  (G_TYPE_CHECK_CLASS_TYPE ((klass), ST_TYPE_THEME_CONTEXT))
+#define ST_THEME_CONTEXT_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS ((obj), ST_TYPE_THEME_CONTEXT, StThemeContextClass))
+
+GType st_theme_context_get_type (void) G_GNUC_CONST;
+
+StThemeContext *st_theme_context_new           (void);
+StThemeContext *st_theme_context_get_for_stage (ClutterStage *stage);
+
+void                        st_theme_context_set_theme      (StThemeContext             *context,
+                                                             StTheme                    *theme);
+StTheme *                   st_theme_context_get_theme      (StThemeContext             *context);
+
+void                        st_theme_context_set_resolution (StThemeContext             *context,
+                                                             gdouble                     resolution);
+double                      st_theme_context_get_resolution (StThemeContext             *context);
+void                        st_theme_context_set_font       (StThemeContext             *context,
+                                                             const PangoFontDescription *font);
+const PangoFontDescription *st_theme_context_get_font       (StThemeContext             *context);
+
+StThemeNode *               st_theme_context_get_root_node  (StThemeContext             *context);
+
+G_END_DECLS
+
+#endif /* __ST_THEME_CONTEXT_H__ */