Add new mlt's Box_Blur ui. It was not working with the automatic one

data/effects/box_blur.xml

+<!DOCTYPE kpartgui>
+<effect tag="box_blur" id="box_blur">
+	<name>BoxBlur</name>
+	<description>Box blur (separate horizontal and vertical blur)</description>
+	<author>Meltytech, LLC</author>
+	<parameter type="animated" name="hradius" max="1000" min="0" default="1" suffix="%">
+		<name>Horizontal multiplicator</name>
+	</parameter>
+	<parameter type="animated" name="vradius" max="1000" min="0" default="1" suffix="%">
+		<name>Vertical multiplicator</name>
+	</parameter>
+</effect>