==Sequencer==

This patch is mostly a usability patch for the sequencer, mainly written by
Anders Gudmundson and twisted a little bit by me.

- Lock Time to other windows
- Possibility to switch the X-Axis between frames and seconds-display
- IPO-Frame Locking for plugins (T-Key)
- Additional Popup to add HD-Sound and Movie at once
- In Timeline-Window: Sequencer windows only playback
- Make the IPOs a little bit IPO-Frame-Lock friendlier (doesn't jump;
  the frame that is drawn has the right dimension)
- Wheel-Mouse buttons make the sequencer window zoom again.
- The "This is not a sound/movie-file message" now reads "... or
  FFMPEG-support not compiled in!" since I learned some prominent
  people who complained, that hdaudio does not work for them ;-)
- Make SPACEKEY open up the "Add Strip"-Popup on the timeline and start
  playback in the preview window.

source/blender/src/sequence.c

@@ -60,6 +60,7 @@
 #include "BIF_space.h"
 #include "BIF_toolbox.h"
 #include "BIF_editsound.h"
+#include "BIF_editseq.h"
 
 #include "BSE_sequence.h"
 #include "BSE_seqeffects.h"
@@ -118,7 +119,7 @@ void new_stripdata(Sequence *seq)
 
 void free_sequence(Sequence *seq)
 {
-	extern Sequence *last_seq;
+	Sequence *last_seq = get_last_seq();
 
 	if(seq->strip) free_strip(seq->strip);
 
@@ -131,7 +132,7 @@ void free_sequence(Sequence *seq)
 		sh.free(seq);
 	}
 
-	if(seq==last_seq) last_seq= 0;
+	if(seq==last_seq) set_last_seq_to_null();
 
 	MEM_freeN(seq);
 }