Fix shwordsplit bug when a basedir contains spaces

The `shwordsplit` option affects all variables and we only need to split
the `$EDITOR` variable. Because of that, using `${=spec}` is a much better
alternative.

More info at
http://zsh.sourceforge.net/Doc/Release/Expansion.html#index-SH_005fWORD_005fSPLIT_002c-toggle

plugins/pj/pj.plugin.zsh

@@ -2,7 +2,6 @@ alias pjo="pj open"
 
 pj () {
     emulate -L zsh
-    setopt shwordsplit
 
     cmd="cd"
     project=$1
@@ -10,7 +9,7 @@ pj () {
     if [[ "open" == "$project" ]]; then
         shift
         project=$*
-        cmd=$EDITOR
+        cmd=${=EDITOR}
     else
         project=$*
     fi