Fix T37485: autocomplete while appending and autocomplete folder behaviour.

This adds functionality to tab-autocomplete folders in the file browser file
field, and the ability to autocomplete .blend files and their sub folders while
linking. If only one match of a blend or a folder is found, it is opened, which
applies to wildcards in the file field now.

Reviewed By: elubie, brecht

Differential Revision: http://developer.blender.org/D20

source/blender/editors/space_file/space_file.c

@@ -396,6 +396,7 @@ static void file_operatortypes(void)
 	WM_operatortype_append(FILE_OT_rename);
 	WM_operatortype_append(FILE_OT_smoothscroll);
 	WM_operatortype_append(FILE_OT_directory);
+	WM_operatortype_append(FILE_OT_filename);
 }
 
 /* NOTE: do not add .blend file reading on this level */