GPasteHistory: init size when loading

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GPasteHistory: reinit size on emptying

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
GPasteHistory: fix biggest election on removal

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
Merge branch '3.0'

* 3.0:
  GPasteHistory: fix biggest election on removal
  GPasteHistory: reinit size on emptying
  GPasteHistory: init size when loading