Flags need to be bitwise orable so give them two's power values
Flags need to be bitwise orable so give them two's power values

Also declare flag operators for CheckoutOptions

KDE/libqgit2,syntheticpp/libqgit2,pav0n/libqgit2,KDE/libqgit2,pav0n/libqgit2,syntheticpp/libqgit2