libpanelapplet-2.0: Add PanelAppletOrient and some missing methods
libpanelapplet-2.0: Add PanelAppletOrient and some missing methods

Fixes bug 590544.

kamanashisroy/aroop,themiwi/vala,GNOME/vala,flobrosch/vala-fixes,flobrosch/vala-fixes,playya/vala,frida/vala,GNOME/vala,playya/vala,kamanashisroy/aroop,themiwi/vala,Jc2k/vala,spidermonkdust/vala,tjol/vala-tjol,tjol/vala-tjol,lovebug356/vala,flobrosch/vala-fixes,GNOME/vala,jessevdk/vala,rvu95/vala,frida/vala,jessevdk/vala,phako/vala,spidermonkdust/vala,jessevdk/vala,severinh/vala,rvu95/vala,kamanashisroy/aroop,Distrotech/vala,Distrotech/vala,severinh/vala,Distrotech/vala,spidermonkdust/vala,lovebug356/vala,phako/vala,severinh/vala,themiwi/vala,Jc2k/vala,frida/vala,GNOME/vala,xdave/pvala,frida/vala,rvu95/vala,tjol/vala-tjol,playya/vala,frida/vala