Update space dispatch:

- drawXXXspace, changeXXXspace, and winqreadXXXspace now receive the area
     and spacedata as explicit arguments, allowing them to access private
     data w/o going through globals.
 - pass the new BWinEvent through to the winqreadXXXspace, allowing future
     access to extended event data.

Removed direct calls to winqreadXXXspace to simulate user actions, replaced
by calls to action functions in edit.c or the appropriate handler.

source/blender/include/BIF_drawseq.h

@@ -33,8 +33,10 @@
 #ifndef BIF_DRAWSEQ_H
 #define BIF_DRAWSEQ_H
 
+struct ScrArea;
 struct Sequence;
-void drawseqspace(void);
+
+void drawseqspace(struct ScrArea *sa, void *spacedata);
 void drawseq(struct Sequence *seq);
 void set_special_seq_update(int val);