Also very all our use of window.onload and switch to using dom:loaded
instead where we can - the main case where we can't is when using a
vector layer as IE will fail unless the page is completely loaded.
If the bounding box of a changeset is much larger than the map then
there seem to be problems with OL not rendering the feature correctly
so reduce the highlight to just be the extent of the map plus a small
margin in that case.
Add a map to the changeset list page, with a bounding box for each
changeset and highighting when the mouse is placed over either a box
on the map or a row of the table.
