[tintinhamans]

Merge after #646 and #671.

Adds a Network section to the options menu for the settings from #646, with Online and LAN tabs: Proxy (Automatic, Disabled, Custom), Server (Automatic, Custom), and the LAN IP. The resolved proxy or host shows in the disabled fields. Cancel after a failed Accept test drops only the connection changes. The dropdowns need the open list click fix of #671. The options panel now fits inside the shell frame, 399 by 511 units with the same padding around and inside every section.

The game version moves from the options menu to the bottom left of the shell frame. It is drawn on the frame on every shell screen that has one and is gone in game.

Settings cleanup: the unused stats_overlay is removed. camera.move_speed_ratio is removed and migrated into ScrollFactor in Options.ini as old * ratio * (width / 2) / (1.6 * 400), clamped below at 1 like upstream (TheSuperHackers#1262), so 1.0 at 2560x1440 gives 100. That formula assumes the right mouse scroll drag of #671, which is measured at 800x600, so the scroll speed no longer depends on the resolution. The Scroll speed slider goes up to 300, since scrolling no longer speeds up with the resolution.

Deployment: the core pack with this OptionsMenu.wnd and MainMenuVersion.wnd needs this code. Without the pack the retail options menu stays, the version stays in it, and settings.json still works.

Tested: z_generals builds. Through the UI rig: the options menu inside the frame at 2560x1440, 1280x720 and 1024x768, the version on the main menu, options, skirmish and replay screens and gone in game, and a migration run (old settings.json to the new shapes, Options.ini gained ScrollFactor).