zsh: Use zplug instead

.gitmodules

@@ -1,3 +1,3 @@
-[submodule "zsh/antigen"]
-	path = zsh/antigen
-	url = https://github.com/zsh-users/antigen.git
+[submodule "zsh/zplug"]
+	path = zsh/zplug
+	url = https://github.com/zplug/zplug.git

zsh/antigen

@@ -1 +0,0 @@
-Subproject commit 58ebc559ff8fe29473d91dc5867d9ccb9d410359

zsh/zplug

@@ -0,0 +1 @@
+Subproject commit 06c6f33bf1543f30d26835867fb73d599e060d04

zsh/zshrc

@@ -14,17 +14,19 @@ fpath=(
 typeset -gU fpath
 
 #
-# Use Antigen
+# Use zplug
 #
 
-if [[ -s "$DOTFILES/zsh/antigen/antigen.zsh" ]]; then
-    source "$DOTFILES/zsh/antigen/antigen.zsh"
+export ZPLUG_HOME=$DOTFILES/zsh/zplug
+if [[ -s "$ZPLUG_HOME/init.zsh" ]]; then
+    source "$ZPLUG_HOME/init.zsh"
 
-    antigen use prezto
+    zplug "sorin-ionescu/prezto", as:plugin, use:init.zsh
 
-    antigen bundle nojhan/liquidprompt
+    zplug "nojhan/liquidprompt", as:plugin
 
-    antigen apply
+    zplug check || zplug install
+    zplug load
 fi