Improve STATIC_ITEM implementation

[thinkyhead]

The STATIC_ITEM macro pushes the cursor down so it can't go above the bottom item. This ensures that when you start to scroll down, the display begins to scroll right away. (Caveats to follow.) This PR makes sure that the screen is re-drawn after one of these cursor corrections.

A more complete solution needs to account for scrolling upward. When scrolling upward the cursor should not be limited, so that you can scroll the top line back into view. You'll notice that the Printer Info screen suffers from this issue, for example. So this will be followed up with more commits once this is worked out.

• Rename START_ROW to START_COL and apply it properly (if it's got to be in there at all).
• Rename menu macro local vars for clarity.
• Update END_SCREEN (used for static-only screens) so it scrolls more simply, merely adjusting the top-line.
• Screens with only a single STATIC_ITEM above MENU_ITEMs will behave as before, pushing the cursor down by one line on the first redraw.
• Add the ability to invert headings and invert some info headings. As a test. (Bold is also possible, if better.)
• Left-justify some info lines, leaving the build info centered.