Adding a page into outline or using Insert dropdown positions it at 0;0

[passiomatic]

In the new web app version of Elm Designer, when user adds a new page by dropping it onto the outline view, or using Insert->Page menu item, the software sets its position to the upper left portion of the workspace (0;0).

This forces the user to "hunt" for the new page within the workspace or use "Show in workspace" context menu item to see it. We can improve the situation in various ways:

1. Enter a special "insert mode" where the app waits for a click into the workspace to place the page. This is a good solution for the Insert->page scenario but it feels strange when user drops items into the outline, so we could fallback to point 2) in the latter case.
2. Using current selected element figure out its containing page and place the new page next to it, on the right or on the left, depending of the space available. This potentially overlaps other pages, but user can always rearrange them. If the are no current selection (that is, the workspace is the current document node) place the page in the center of the visibile portion of the workspace.
3. Always place the page in the middle on the visibile portion of the workspace. This is probably the less surprising, straight behavior to keep. It has the same limitation on the point 2), potentially it makes the new page overlapping existing pages.