Fix command letter casing.
Fix command letter casing.

SendRaw and SendRawf have title casing.
oniichaNj/go-ircevent,alaska/go-ircevent,HenrySlawniak/go-ircevent,Elemental-IRCd/irc,dainis/go-ircevent,SeanThomasWilliams/go-ircevent,pratikmallya/go-ircevent,DanielOaks/girc-go