Bug 457502

SUMMARY
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One of my most often-needed effects in Kdenlive is to draw animated shapes.  Lines, rectangles, ovals, maybe some others.  The vast majority of the time, I just need to keyframe a simple line or rectangle from point A to point B, with a solid color.  Using images for this purpose is very cumbersome.  

Some additional options would be nice, which I've included below, but just being able to draw some simple geometry would be extremely useful.
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Ideally, the shapes would have the following basic properties:
* X1, Y1, X2, Y2 (keyframable) - in the case of oval, it would be a bounding box
* Stroke width (keyframable)
* Stroke color/opacity (keyframable)
* Fill color/opacity (keyframable)
* Stroke cap -- rounded/squared/arrows (not keyframable, used for line endings)


Some extra, less important wishlist items:
* Arrows (mentioned above) on line endings with width/length/style properties
* Triangles/Polygons, with Point(s) X/Y -- (keyframable)
* Polygon segment edge profiles -- rounded/squared/beveled (not keyframable)
* Fill with image (with options similar to CSS background-size, such as cover/contain)
* Fill with gradient (keyframable)