zsh: add plugin and EDITOR env var

zshrc

@@ -68,7 +68,7 @@ ZSH_THEME="gianu"
 # Custom plugins may be added to $ZSH_CUSTOM/plugins/
 # Example format: plugins=(rails git textmate ruby lighthouse)
 # Add wisely, as too many plugins slow down shell startup.
-plugins=(git)
+plugins=(git history-substring-search)
 
 source $ZSH/oh-my-zsh.sh
 
@@ -108,6 +108,9 @@ bindkey -v
 export PATH=$HOME/local/bin:$PATH
 export PATH=$HOME/bin:$PATH
 
+# General environment
+export EDITOR=vim
+
 # set up asdf (must be after paths)
 . $HOME/.asdf/asdf.sh