zsh: source .zshenv for system-specific configuration

zsh/init.zsh

@@ -1,4 +1,5 @@
 zshrc=~/.zshrc
+zshenv=~/.zshenv
 if [ -z $zshrc ]; then
 	echo "Err: Cannot find dotfile directory."
 	exit -1
@@ -48,3 +49,10 @@ source $zsh_dir/commands.zsh
 # KEYBIND initialisation
 
 source $zsh_dir/keybind.zsh
+
+
+# SYSTEM-SPECIFIC initialisation
+
+if [ -z $zshenv ]; then
+	source $zshenv
+fi