Add support for multiple maps/pages

[lostcarpark]

ConCarte is a fantastic resource for convention maps, but currently it requires everything to be on a single map.

I think for most conventions this is advisable, but for very large conventions, or conventions split over multiple sites, I think it could be unwieldy to fit everything on a single map or page.

It would be great if there was an optional to have several map pages, each with it's own background image and set of rooms.

Perhaps there could be a page listing locked to an edge of the page for selecting the current page, with the current page highlighted.

[aJanuary]

I think we probably do need to provide support for this, as it feels like a natural extension. But I've been going back and forth whether I think it's actually beneficial.

If we're talking about multiple buildings, then what value does switching maps give you over and above panning to the other map? If it's just about quick access to the other buildings, we could have buttons to jump to sections of the map.

And the cost of switching maps is you lose context. If I'm trying to find my way from a room in one building to a room in another building, it feels like switching out the whole map will be disorientating, versus panning around where I can smoothly transition the context.

For buildings with multiple floors, switching out maps is probably useful, because it keeps the frame of reference. I'm staring at the stairs, switch floors, and I know where I will come out.

[lostcarpark]

You're probably right that it would be more useful to combine multiple buildings onto a single map and split by level.

However, I think it's something the app can be fairly agnostic about. Ultimately it will be up to the convention to figure out if splitting the map is warranted, and how best to lay it out.

In the sample map of the Telford convention centre, there are two levels, but they have quite different layouts, so it can be challenging to relate where things on the upper and lower levels are in relation to each other. Splitting that into two pages might make that easier, so long as the zoom and position remained the same when switching pages.

[aJanuary]

I've made a stab at implementing multiple maps in #6

I chose to, rather than keeping the zoom and pan from level 1 when you switch to level 2, use the previous zoom and pan from level 2. I think this is important for being able to find your way from a room on level 1 to a room on level 2.

I'm going to leave the PR open for a week or two to give people an opportunity to provide feedback on how well it works/doesn't work.

[lostcarpark]

I will work with @bennis1980 this week on making his Gaelcon map multi-level, and hopefully provide feedback this week.