ensure getChildren() is called on an instance of Share_Backend_Collection

Fix #4940

when _ is left in namespace and files are named after their classes the autoloader will also find classes in the lib folder of an app
its magic!

use 96x96 as 64x64 thumbnails in conflicts dialog, 64x64 looks very blocky ... maybe something is wrong there

use places/folder icon,
move link construction to JS,
only show icon on hover,
use 'searchresult' as css class name,
add filter/unfilter methods,
highlight searched files in current filelist
only filter when correct FileList is present