- fix unlink between decoupled elements
- fix unlink between decoupled elements

Original commit message from CVS:
- fix unlink between decoupled elements
- clear the entry point of a group when we remove the element
- fix a potential problem in _merge_groups that could be triggered when
someone is holding an extra refcount to the group.

justinjoy/gstreamer,justinjoy/gstreamer,lubosz/gstreamer,Lachann/gstreamer,jpxiong/gstreamer,lovebug356/gstreamer,drothlis/gstreamer,collects/gstreamer,cfoch/gstreamer,jpakkane/gstreamer,Distrotech/gstreamer,StreamUtils/gstreamer,mparis/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,ylatuya/gstreamer,magcius/gstreamer,lubosz/gstreamer,collects/gstreamer,StreamUtils/gstreamer,Distrotech/gstreamer,Distrotech/gstreamer,ensonic/gstreamer,magcius/gstreamer,centricular/gstreamer,mrchapp/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,magcius/gstreamer,cablelabs/gstreamer,collects/gstreamer,mrchapp/gstreamer,cfoch/gstreamer,lubosz/gstreamer,ylatuya/gstreamer,shelsonjava/gstreamer,ylatuya/gstreamer,magcius/gstreamer,ahmedammar/platform_external_gst_gstreamer,cfoch/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,krieger-od/gstreamer,jpxiong/gstreamer,justinjoy/gstreamer,drothlis/gstreamer,lubosz/gstreamer,krieger-od/gstreamer,cablelabs/gstreamer,drothlis/gstreamer,krieger-od/gstreamer,Lachann/gstreamer,ensonic/gstreamer,jpxiong/gstreamer,krieger-od/gstreamer,krichter722/gstreamer,cfoch/gstreamer,krichter722/gstreamer,mrchapp/gstreamer,ahmedammar/platform_external_gst_gstreamer,shelsonjava/gstreamer,mparis/gstreamer,ylatuya/gstreamer,mparis/gstreamer,collects/gstreamer,lovebug356/gstreamer,lovebug356/gstreamer,krichter722/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,Lachann/gstreamer,cablelabs/gstreamer,StreamUtils/gstreamer,mparis/gstreamer,justinjoy/gstreamer,jpxiong/gstreamer,centricular/gstreamer,surround-io/gstreamer,drothlis/gstreamer,surround-io/gstreamer,jpakkane/gstreamer,ahmedammar/platform_external_gst_gstreamer,lovebug356/gstreamer,cfoch/gstreamer,justinjoy/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,centricular/gstreamer,mparis/gstreamer,StreamUtils/gstreamer,Distrotech/gstreamer,collects/gstreamer,krieger-od/gstreamer,centricular/gstreamer,krichter722/gstreamer,ylatuya/gstreamer,surround-io/gstreamer,ensonic/gstreamer,magcius/gstreamer,Distrotech/gstreamer,lovebug356/gstreamer,mrchapp/gstreamer,drothlis/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,mrchapp/gstreamer,jpakkane/gstreamer,ensonic/gstreamer,jpakkane/gstreamer,Lachann/gstreamer,Lachann/gstreamer,lubosz/gstreamer,ahmedammar/platform_external_gst_gstreamer,ensonic/gstreamer,ahmedammar/platform_external_gst_gstreamer