This commit adds two of my recent animation editing related patches:

#5061 - Ipo/Action 'Cleaning'
#5071 - 'Only Needed' Keyframing Option

====================

* IPO/Action 'Cleaning':
It removes un-necessary keyframes from individual ipo curves.
- In both editors, the hotkey is currently the OKEY.  Also accesable from menus of each editor.
- There is currently a 'threshold' popup. This sets the value that the cleaner uses to determine if two keys have same time/value

There are a few improvements that could still be made, such as:
- There are a few cases that it still doesn't handle yet, such as when un-needed keyframes lie on a linear line (and similiar cases). This shall be improved soon.
- Also, for some reason, after running cleaning while in ipo editor editmode, all but the active curve are hidden.

====================

* 'Only Needed' Keyframing Option:
This patch adds a new keyframing option for objects and bones. It only adds keyframes where they are needed, judging from the surrounding points on that curve.

Notes about this keyframing option:
- Works like the existing 'Avail' option, except it checks if the keyframe
is needed.
- Currently uses hardcoded threshold for determining if same value.

[quote]
/* Cases where keyframes should not be added:
*       1. Keyframe to be added bewteen two keyframes with similar values
*       2. Keyframe to be added between two keyframes with similar times
*       3. Keyframe lies at point that intersects the linear line between two
keyframes
*/
[/unquote]

source/blender/src/space.c

@@ -2373,6 +2373,9 @@ static void winqreadipospace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 			toggle_blockhandler(sa, IPO_HANDLER_PROPERTIES, UI_PNL_TO_MOUSE);
 			doredraw= 1;
 			break;
+		case OKEY: 
+			clean_ipo(sipo->ipo, 1);
+			break;
 		case RKEY:
 			if((G.qual==0))
 				ipo_record();