core: allow percentage on width/height (refs #323)
core: allow percentage on width/height (refs #323)

shakin/clappr,clappr/clappr,dayvson/clappr,dayvson/clappr,flavioribeiro/clappr,irongomme/clappr,kelonye/clappr,dayvson/clappr,Pyrotoxin/clappr,clappr/clappr,clappr/clappr,irongomme/clappr,Peer5/clappr,tarkanlar/clappr,MariadeAnton/clappr,Peer5/clappr,jfairley/clappr,flavioribeiro/clappr,Pyrotoxin/clappr,burakkp/clappr,leandromoreira/clappr,Metrakit/clappr,wxmfront/clappr,leandromoreira/clappr,MariadeAnton/clappr,burakkp/clappr,shakin/clappr,MariadeAnton/clappr,irongomme/clappr,jfairley/clappr,Pyrotoxin/clappr,tarkanlar/clappr,leandromoreira/clappr,wxmfront/clappr,kelonye/clappr,Metrakit/clappr,tjenkinson/clappr,tjenkinson/clappr,kelonye/clappr,jfairley/clappr,shakin/clappr,tarkanlar/clappr,Metrakit/clappr,flavioribeiro/clappr,tjenkinson/clappr,burakkp/clappr,wxmfront/clappr,Peer5/clappr