[vim] Adjust split size when --header option is set
[vim] Adjust split size when --header option is set

Close #622

lululau/fzf,stuha/wbr-zsh,infokiller/fzf,janlazo/fzf,janlazo/fzf,wilywampa/fzf,infokiller/fzf,qiemem/fzf,lululau/fzf,janlazo/fzf,lululau/fzf,wilywampa/fzf,infokiller/fzf,tomfitzhenry/pkg-fzf,wilywampa/fzf,tomfitzhenry/pkg-fzf,qiemem/fzf,qiemem/fzf,tomfitzhenry/pkg-fzf,junegunn/fzf,junegunn/fzf,junegunn/fzf