Software versions, in one place

Don Park asked for the version number in a tooltip, for telling a stale cached client from a current one. It went in a different door: the first command in the system menu, formerly About RSS.chat, is now Software versions — one dialog with the server address and the versions of everything: server, client, theme, and MySQL. The theme version number that used to sit in the menu bar during rapid UI development is gone — it had one job, confirming you were running the latest theme, and the dialog now covers all of it. Work by DW; his reply to Don is 353.