qt: Use parent-child relation to manage lifetime of OptionsModel object
qt: Use parent-child relation to manage lifetime of OptionsModel object

Both BitcoinApplication and OptionsModel classes are derived from the
QObject class, therefore a parent-child relation could be established to
manage the lifetime of an OptionsModel object.
This commit does not change behavior.

bitcoinsSG/bitcoin,jamesob/bitcoin,ElementsProject/elements,pataquets/namecoin-core,MeshCollider/bitcoin,litecoin-project/litecoin,anditto/bitcoin,tecnovert/particl-core,qtumproject/qtum,AkioNak/bitcoin,GroestlCoin/bitcoin,yenliangl/bitcoin,rnicoll/dogecoin,mruddy/bitcoin,bitcoinknots/bitcoin,jlopp/statoshi,andreaskern/bitcoin,jlopp/statoshi,tecnovert/particl-core,ajtowns/bitcoin,sipsorcery/bitcoin,litecoin-project/litecoin,dscotese/bitcoin,achow101/bitcoin,instagibbs/bitcoin,namecoin/namecore,Xekyo/bitcoin,andreaskern/bitcoin,namecoin/namecoin-core,GroestlCoin/bitcoin,GroestlCoin/bitcoin,jamesob/bitcoin,jnewbery/bitcoin,cdecker/bitcoin,fanquake/bitcoin,Xekyo/bitcoin,achow101/bitcoin,fujicoin/fujicoin,dscotese/bitcoin,namecoin/namecoin-core,anditto/bitcoin,achow101/bitcoin,instagibbs/bitcoin,pataquets/namecoin-core,mm-s/bitcoin,JeremyRubin/bitcoin,tecnovert/particl-core,bitcoin/bitcoin,mm-s/bitcoin,n1bor/bitcoin,qtumproject/qtum,particl/particl-core,midnightmagic/bitcoin,mruddy/bitcoin,jamesob/bitcoin,midnightmagic/bitcoin,practicalswift/bitcoin,instagibbs/bitcoin,MeshCollider/bitcoin,sstone/bitcoin,jamesob/bitcoin,bitcoin/bitcoin,yenliangl/bitcoin,jnewbery/bitcoin,practicalswift/bitcoin,midnightmagic/bitcoin,Sjors/bitcoin,EthanHeilman/bitcoin,fanquake/bitcoin,domob1812/namecore,n1bor/bitcoin,sipsorcery/bitcoin,lateminer/bitcoin,kallewoof/bitcoin,MeshCollider/bitcoin,ajtowns/bitcoin,prusnak/bitcoin,jnewbery/bitcoin,JeremyRubin/bitcoin,jonasschnelli/bitcoin,bitcoinknots/bitcoin,achow101/bitcoin,pataquets/namecoin-core,bitcoinsSG/bitcoin,jambolo/bitcoin,bitcoinsSG/bitcoin,cdecker/bitcoin,domob1812/bitcoin,litecoin-project/litecoin,domob1812/bitcoin,anditto/bitcoin,fujicoin/fujicoin,yenliangl/bitcoin,Xekyo/bitcoin,n1bor/bitcoin,apoelstra/bitcoin,jambolo/bitcoin,fujicoin/fujicoin,fujicoin/fujicoin,domob1812/namecore,litecoin-project/litecoin,JeremyRubin/bitcoin,jlopp/statoshi,yenliangl/bitcoin,particl/particl-core,andreaskern/bitcoin,ElementsProject/elements,Sjors/bitcoin,pstratem/bitcoin,domob1812/namecore,Xekyo/bitcoin,midnightmagic/bitcoin,dscotese/bitcoin,jnewbery/bitcoin,lateminer/bitcoin,ElementsProject/elements,jambolo/bitcoin,alecalve/bitcoin,lateminer/bitcoin,Sjors/bitcoin,jonasschnelli/bitcoin,prusnak/bitcoin,cdecker/bitcoin,bitcoinsSG/bitcoin,apoelstra/bitcoin,apoelstra/bitcoin,ajtowns/bitcoin,AkioNak/bitcoin,EthanHeilman/bitcoin,GroestlCoin/GroestlCoin,ElementsProject/elements,fanquake/bitcoin,practicalswift/bitcoin,practicalswift/bitcoin,litecoin-project/litecoin,bitcoinknots/bitcoin,andreaskern/bitcoin,cdecker/bitcoin,sstone/bitcoin,pstratem/bitcoin,AkioNak/bitcoin,ElementsProject/elements,instagibbs/bitcoin,ajtowns/bitcoin,pataquets/namecoin-core,lateminer/bitcoin,prusnak/bitcoin,Sjors/bitcoin,jnewbery/bitcoin,sipsorcery/bitcoin,kallewoof/bitcoin,AkioNak/bitcoin,fujicoin/fujicoin,EthanHeilman/bitcoin,MarcoFalke/bitcoin,tecnovert/particl-core,mruddy/bitcoin,jambolo/bitcoin,cdecker/bitcoin,rnicoll/dogecoin,ElementsProject/elements,mruddy/bitcoin,fanquake/bitcoin,litecoin-project/litecoin,mm-s/bitcoin,namecoin/namecoin-core,tecnovert/particl-core,lateminer/bitcoin,rnicoll/dogecoin,kallewoof/bitcoin,apoelstra/bitcoin,n1bor/bitcoin,andreaskern/bitcoin,yenliangl/bitcoin,practicalswift/bitcoin,kallewoof/bitcoin,rnicoll/bitcoin,fujicoin/fujicoin,qtumproject/qtum,particl/particl-core,AkioNak/bitcoin,JeremyRubin/bitcoin,alecalve/bitcoin,instagibbs/bitcoin,kallewoof/bitcoin,alecalve/bitcoin,rnicoll/bitcoin,domob1812/namecore,GroestlCoin/GroestlCoin,bitcoinknots/bitcoin,MarcoFalke/bitcoin,rnicoll/bitcoin,rnicoll/bitcoin,EthanHeilman/bitcoin,sipsorcery/bitcoin,alecalve/bitcoin,anditto/bitcoin,MeshCollider/bitcoin,jlopp/statoshi,rnicoll/dogecoin,prusnak/bitcoin,namecoin/namecore,jonasschnelli/bitcoin,domob1812/bitcoin,apoelstra/bitcoin,prusnak/bitcoin,GroestlCoin/bitcoin,anditto/bitcoin,prusnak/bitcoin,bitcoin/bitcoin,sipsorcery/bitcoin,namecoin/namecore,pstratem/bitcoin,bitcoin/bitcoin,practicalswift/bitcoin,pstratem/bitcoin,domob1812/bitcoin,apoelstra/bitcoin,bitcoinsSG/bitcoin,andreaskern/bitcoin,Xekyo/bitcoin,namecoin/namecoin-core,dscotese/bitcoin,jonasschnelli/bitcoin,mruddy/bitcoin,bitcoinsSG/bitcoin,GroestlCoin/GroestlCoin,rnicoll/bitcoin,AkioNak/bitcoin,jamesob/bitcoin,rnicoll/dogecoin,qtumproject/qtum,GroestlCoin/bitcoin,alecalve/bitcoin,EthanHeilman/bitcoin,qtumproject/qtum,bitcoinknots/bitcoin,pataquets/namecoin-core,dscotese/bitcoin,Xekyo/bitcoin,bitcoin/bitcoin,alecalve/bitcoin,pstratem/bitcoin,particl/particl-core,namecoin/namecoin-core,jlopp/statoshi,sstone/bitcoin,mm-s/bitcoin,n1bor/bitcoin,GroestlCoin/GroestlCoin,pataquets/namecoin-core,rnicoll/bitcoin,jamesob/bitcoin,lateminer/bitcoin,qtumproject/qtum,n1bor/bitcoin,tecnovert/particl-core,bitcoin/bitcoin,EthanHeilman/bitcoin,MarcoFalke/bitcoin,jambolo/bitcoin,yenliangl/bitcoin,domob1812/bitcoin,Sjors/bitcoin,namecoin/namecoin-core,dscotese/bitcoin,GroestlCoin/GroestlCoin,domob1812/namecore,qtumproject/qtum,jonasschnelli/bitcoin,MeshCollider/bitcoin,namecoin/namecore,midnightmagic/bitcoin,domob1812/namecore,MarcoFalke/bitcoin,domob1812/bitcoin,sstone/bitcoin,mruddy/bitcoin,anditto/bitcoin,cdecker/bitcoin,GroestlCoin/bitcoin,namecoin/namecore,particl/particl-core,fanquake/bitcoin,mm-s/bitcoin,MarcoFalke/bitcoin,GroestlCoin/GroestlCoin,achow101/bitcoin,ajtowns/bitcoin,sipsorcery/bitcoin,sstone/bitcoin,achow101/bitcoin,midnightmagic/bitcoin,JeremyRubin/bitcoin,fanquake/bitcoin,MeshCollider/bitcoin,mm-s/bitcoin,namecoin/namecore,pstratem/bitcoin,particl/particl-core,jambolo/bitcoin,MarcoFalke/bitcoin,ajtowns/bitcoin,JeremyRubin/bitcoin,jlopp/statoshi,instagibbs/bitcoin,kallewoof/bitcoin,sstone/bitcoin