Picture Frames: Remove "Path" from file labels

As @badukibaduki pointed out in #3420, it's misleading to label the
picture selections "Picture 1 Path", "Picture 2 Path", etc.
We only allow the user to select existing Project Files, so they
can't load an arbitrary file path.

Author: ferdnyc

src/blender/picture_frames_4.xml

@@ -11,28 +11,28 @@
 		<default>TitleFileName</default>
 	</param>
 
-	<param name="project_files1" type="dropdown" title="Picture 1 Path" description="">
+	<param name="project_files1" type="dropdown" title="Picture 1" description="">
 		<values>
 			<value name="" num=""/>
 		</values>
 		<default></default>
 	</param>
 
-	<param name="project_files2" type="dropdown" title="Picture 2 Path" description="">
+	<param name="project_files2" type="dropdown" title="Picture 2" description="">
 		<values>
 			<value name="" num=""/>
 		</values>
 		<default></default>
 	</param>
 
-	<param name="project_files3" type="dropdown" title="Picture 3 Path" description="">
+	<param name="project_files3" type="dropdown" title="Picture 3" description="">
 		<values>
 			<value name="" num=""/>
 		</values>
 		<default></default>
 	</param>
 
-	<param name="project_files4" type="dropdown" title="Picture 4 Path" description="">
+	<param name="project_files4" type="dropdown" title="Picture 4" description="">
 		<values>
 			<value name="" num=""/>
 		</values>