vim styling updates
vim styling updates

* change cursor when in insert mode
* change to onedark theme
* enable true colors support when not in tmux
* change NERDTree folder characters

dyong0/dotfiles,OctavianRotari/dotfiles,abhisood/dotfiles,nicknisi/dotfiles,nicknisi/dotfiles,OctavianRotari/dotfiles,nicknisi/dotfiles,NerdPad/dotfiles