[PengeTasksPane] Adopt Tasks sorting method
[PengeTasksPane] Adopt Tasks sorting method

Use the same sorting method as Tasks by copying code from libkoto.

Fixes: MB#5179

kkszysiu/gnomesocial,meego-netbook-ux/meego-panel-myzone,kkszysiu/gnomesocial,meego-netbook-ux/meego-panel-myzone