Sync 2-column setting state

[JayPanoz]

At the moment the “auto/1 column/2 columns” setting is not reacting to what is really happening in the logic. Mainly:

• it is not disabled for conditions where it can’t be used e.g. the window’s width is not large enough based on the minimum line-length set in preferences;
• it isn’t updated dynamically based on the minimum line-length logic when set – switching from 1 to 2 columns, and back – when resizing the window/changing font-size.