vapigen: Support setting the parent of a symbol.
vapigen: Support setting the parent of a symbol.

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