Cleaning point sprite plugin

A warning was caused by a redefined signal in a child class.
Another warning was caused by a call to a property which
does not exist any more.

Change-Id: I2edf10921807230becf0f28edec2b076e3c662d4
Merge topic 'cleaning_point_sprite' into next

d4d4adb7 Cleaning point sprite plugin
plugins: initialize static plugins earlier

Change-Id: I95ccfa0e10ef5176d78921cc66a7ed3cb7cdc6c4
Merge topic 'static-plugin-loading' into next

cb009429 plugins: initialize static plugins earlier