Make curve decimation only take into account the selected curve points

Previously the decimation would take the whole curve into account when
decimating and not just the selected part.

This also contains various smaller bug fixes for the fcurve decimation.

Reviewed By: Sybren

Differential Revision: http://developer.blender.org/D6286

source/blender/blenkernel/intern/curve_decimate.c

@@ -269,11 +269,11 @@ uint BKE_curve_decimate_bezt_array(BezTriple *bezt_array,
     if (a == HD_VECT) { \
       a = HD_FREE; \
     } \
-    else if (a == HD_AUTO) { \
+    else if (a == HD_AUTO || a == HD_AUTO_ANIM) { \
       a = HD_ALIGN; \
     } \
     /* opposite handle */ \
-    if (b == HD_AUTO) { \
+    if (b == HD_AUTO || b == HD_AUTO_ANIM) { \
       b = HD_ALIGN; \
     } \
   } \