Refactor BKE_blender into separate headers

- BKE_blender_version.h (only version defines & versionstr).
- BKE_blender_copybuffer.h (currently only used for view3d copy/paste).
- BKE_blender_undo.h (global undo functions).
- BKE_blendfile.h (high level blend file read/write API).

source/blender/python/intern/bpy.c

@@ -35,7 +35,7 @@
 
 #include "BKE_appdir.h"
 #include "BKE_global.h" /* XXX, G.main only */
-#include "BKE_blender.h"
+#include "BKE_blender_version.h"
 #include "BKE_bpath.h"
 
 #include "RNA_types.h"

source/blender/python/intern/bpy_app.c

@@ -48,7 +48,7 @@
 #include "BLI_utildefines.h"
 
 #include "BKE_appdir.h"
-#include "BKE_blender.h"
+#include "BKE_blender_version.h"
 #include "BKE_global.h"
 
 #include "DNA_ID.h"

source/blender/python/intern/bpy_library_write.c

@@ -35,7 +35,7 @@
 #include "BLI_path_util.h"
 
 #include "BKE_library.h"
-#include "BKE_blender.h"
+#include "BKE_blendfile.h"
 #include "BKE_global.h"
 #include "BKE_main.h"
 #include "BKE_report.h"