Multi-command dialog buttons and fewer update reminders

Dialogs

• “Run command” and “Run as console” buttons now accept up to 16 commands, one per line. Commands run top to bottom and stop at the first failure. Player commands use the clicking player’s permissions; console commands run as the console.
• With MC GUI on the same server, a drawn dialog opened after an MC GUI page now draws correctly: its resource pack is put back on top first, in a single reload.

Update Checks

• Updates are now checked once at startup instead of every six hours, avoiding repeated reminders to the console and online operators. Operators who join later still receive update notices.