working prototype for editing large geometries, needs more work though
move creation of the spatial index to select feature
work in progress on updating the spatial index after a vertex has been moved
use the closest hit from the index search and not the first one
use vertexIndex to get correct winding order
use distanceSquaredToSegment instead as suggested by @ahocevar
remove accidentally committed swap file
do not hover when we are dragging
Do not rely on outdated _index

Instead, calculate the index with indexOf - should be no problem since we
only do this once.

Also made some cleanups to remove side effects and reduce array lookups.
merge with ahocevar/largegeom
later deletion of _next and _previous
deactivate the hover handler when the feature is unselected
centralize creation of virtual vertices
move the code into a mixin
document and clean up
change directory structure to be more logical
restore previous functionality of collectVertices
add some tests
incorporate @ahocevar's review
Merge pull request #1080 from bartvde/largegeom

Editing of large geometries (r=@ahocevar)