[DDC-1014] Add abstract non-implemented methods for datediff, add and sub.
[DDC-1014] Add abstract non-implemented methods for datediff, add and sub.

easybiblabs/dbal,sarcher/dbal,kupishkis/dbal,shivergard/dbal,Ocramius/dbal,Tobion/dbal,Tobion/dbal,DataSyntax/dbal,mikeSimonson/dbal,mihai-stancu/dbal,vutung2311/dbal,adrienbrault/dbal,shivergard/dbal,stchr/dbal,drieschel/dbal,kimhemsoe/dbal,hason/dbal,bspeterson/dbal,DHager/dbal,stof/dbal,PureBilling/dbal,lafourchette/dbal,mathroc/dbal,mbeccati/dbal,mariuz/dbal,tk-s/dbal,mihai-stancu/dbal,adrienbrault/dbal,bspeterson/dbal,vortgo/dbal,PowerKiKi/dbal,helicon-os/doctrine-dbal,easybiblabs/dbal,AlexDpy/dbal,PureBilling/dbal,v-bartusevicius/dbal,doctrine/dbal,AlexDpy/dbal,DataSyntax/dbal,zeroedin-bill/dbal,mRoca/dbal,mariuz/dbal,vortgo/dbal,hason/dbal,easybiblabs/dbal,BenMorel/dbal,vutung2311/dbal,webonyx/dbal,drieschel/dbal,mathroc/dbal,DHager/dbal,stof/dbal,LionwareSolutions/dbal,helicon-os/doctrine-dbal,mbeccati/dbal,mihai-stancu/doctrine-dbal,zeroedin-bill/dbal,lcobucci/dbal,sarcher/dbal,v-bartusevicius/dbal,doctrine/dbal,PowerKiKi/dbal,lafourchette/dbal,mihai-stancu/doctrine-dbal,nfrignani/dbal,PowerKiKi/dbal,hason/dbal,gencer/dbal,adrienbrault/dbal,deeky666/dbal,sarcher/dbal,kupishkis/dbal,nfrignani/dbal,janschoenherr/dbal,LionwareSolutions/dbal,webonyx/dbal,cassvail/dbal,arima-ryunosuke/dbal,wuxu92/dbal,cassvail/dbal,mariuz/dbal,mRoca/dbal,BenMorel/dbal,mikeSimonson/dbal,wuxu92/dbal,LionwareSolutions/dbal,kimhemsoe/dbal,Ocramius/dbal,stchr/dbal,arima-ryunosuke/dbal,gencer/dbal,deeky666/dbal,tk-s/dbal,janschoenherr/dbal,webonyx/dbal,lcobucci/dbal,kupishkis/dbal,arima-ryunosuke/dbal