Add fnm install function

plugins/nvm/nvm.plugin.zsh

@@ -1,7 +1,8 @@
 typeset -a chpwd_functions __chromaz_extra_left
 # fnm
 FNM_PATH="${XDG_DATA_HOME:-$HOME/.local/share}/fnm"
-if [ -d "$FNM_PATH" ]; then
+
+_setup-fnm() {
 	export PATH="$FNM_PATH:$PATH"
 	eval "$(fnm env --use-on-cd --version-file-strategy recursive)"
 	FNM_DEFAULT=${$(readlink $FNM_PATH/aliases/default):h:t}
@@ -12,6 +13,10 @@ if [ -d "$FNM_PATH" ]; then
 		echo "nodejs: ${node_version}"
 	}
 	__chromaz_extra_left+=_prompt_fnm_version
+}
+
+if [ -d "$FNM_PATH" ]; then
+	_setup-fnm
 elif [ -d "$HOME/.nvm" ]; then
 	export NVM_DIR="$HOME/.nvm"
 	nvm() {
@@ -46,6 +51,14 @@ elif [ -d "$HOME/.nvm" ]; then
 	}
 	__chromaz_extra_left+=_prompt_nvm_version
 else
-	return
+	install-fnm() {
+		mkdir -p "$FNM_PATH" &>/dev/null
+		if ! curl -L https://github.com/Schniz/fnm/releases/latest/download/fnm-linux.zip | funzip > $FNM_PATH/fnm ; then
+		  echo "Download failed.  Check that the release/filename are correct."
+		  return 1
+		fi
+		chmod u+x "$FNM_PATH/fnm"
+		_setup-fnm
+	}
 fi