Fixes underscore methods and reduces code duplication.
Fixes underscore methods and reduces code duplication.

Fixes #170. 

There is now a central (currently private) method for getting the resolved virtuals of a model.
princesust/bookshelf,offlinehacker/bookshelf,zdespolit/bookshelf,tjwudi/bookshelf,skevy/bookshelf,TNuzzi/bookshelf,tbutman/bookshelf,lanetix/bookshelf,chrisbroome/bookshelf,princesust/bookshelf,stonegithubs/bookshelf,joshturn/bookshelf,TinOo512/bookshelf,jordansexton/bookshelf,princesust/bookshelf,TNuzzi/bookshelf,vellotis/bookshelf,cspotcode/bookshelf,jadengore/bookshelf,jadengore/bookshelf,stridentbean/bookshelf,stonegithubs/bookshelf,bsiddiqui/bookshelf,tjwudi/bookshelf,shadedprofit/bookshelf,rbong/bookshelf,mdboop/bookshelf,lanetix/bookshelf,vellotis/bookshelf,stridentbean/bookshelf,tgriesser/bookshelf,sxhao/bookshelf,patbenatar/bookshelf,zubeio/bookshelf,offlinehacker/bookshelf,joshturn/bookshelf,nodeonly/bookshelf,MadcapJake/bookshelf,chuym/bookshelf,zdespolit/bookshelf,VideoAmp/bookshelf,sxhao/bookshelf,jadengore/bookshelf,chuym/bookshelf,nodeonly/bookshelf,tgriesser/bookshelf,patbenatar/bookshelf,tbutman/bookshelf,mdboop/bookshelf,chrisbroome/bookshelf,shadedprofit/bookshelf,jordansexton/bookshelf,VideoAmp/bookshelf,zdespolit/bookshelf,sanchesic89/bookshelf,vellotis/bookshelf,cspotcode/bookshelf,apla/bookshelf,sanchesic89/bookshelf,bsiddiqui/bookshelf,rbong/bookshelf,tjwudi/bookshelf,joshturn/bookshelf,zubeio/bookshelf,MadcapJake/bookshelf,dougshamoo/bookshelf,stridentbean/bookshelf,offlinehacker/bookshelf,shadedprofit/bookshelf,shaunstanislaus/bookshelf,mdboop/bookshelf,stonegithubs/bookshelf,bookshelf/bookshelf,tbutman/bookshelf,dougshamoo/bookshelf,nodeonly/bookshelf,VideoAmp/bookshelf,MadcapJake/bookshelf,sanchesic89/bookshelf,bookshelf/bookshelf,TinOo512/bookshelf,seegno-forks/bookshelf,skevy/bookshelf,zubeio/bookshelf,lanetix/bookshelf,chuym/bookshelf,sxhao/bookshelf,dougshamoo/bookshelf,skevy/bookshelf,apla/bookshelf,patbenatar/bookshelf,shaunstanislaus/bookshelf,shaunstanislaus/bookshelf,seegno-forks/bookshelf,TNuzzi/bookshelf