Menu as an 8 / 4 / 4 grid with words: slots on top, Settings WebUI Grid Slides, Exit Reset Debug UDP #177

The top row holds the 8 slots only; the mode letters move down as words, two rows of four:

[ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ]
[ Settings | WebUI  | Grid   | Slides ]
[ Exit     | Reset  | Debug  | UDP    ]

• Q → Grid (multi-view, 2×2 or 3×3), S → Slides (key frames only, Menu: S — slide mode, multi-view on key frames only for every camera #108), D → Debug (cell text), U → UDP (the U cell full screen, Receive plain RTP from Majestic outgoing over UDP (unicast and multicast) #68/U cell: receive the pushed UDP RTP stream (udp://@:5600) in the ninth cell and the U view #87). On / active keep the orange fill, the focus keeps the blue frame (Menu: the focus and the "on" state look alike (both a coloured border) #143).
• Every lower cell is exactly two slots wide: the slots and the four columns share one grid, the menu's width is set by the widest word.
• Settings and WebUI stay in place in multi-view and the U view, greyed and disabled, instead of hiding the row, so the grid does not jump.
• Remote: Down from a slot goes to the column under it, Up from a column to its left slot; Left / Right move within a row. The menu opens with the focus where it is today (active slot, Grid in multi-view, UDP in the U view, Menu cannot be operated with the remote control #91).
• Exit keeps the small version text, the word centred (Menu: Settings, WebUI, Exit and Reset centred in their halves #176).
• README (EN/RU/ZH) menu table and screenshots updated.