Rewrite script processing a bit

- Instead of using eval() we now use a proper VM Context
- As a result, any scripting errors will now give a more useful filename and line number.
- However, some things may break, if they are dependant on variables we are not allowing in the context.

zefie_wtvp_minisrv/WTVClientSessionData.js

@@ -66,6 +66,10 @@ class WTVClientSessionData {
         this.mailstore = new WTVMail(this.minisrv_config, this)
     }
 
+    createWTVSecSession() {
+        return new WTVSec(this.minisrv_config)
+    }
+
     getAccountTotalUnreadMessages() {
         if (!this.isRegistered()) return false; // unregistered
         if (this.user_id > 0) return false; // not primary user or pre-login