Look through all stylesheets for sprites

Needed for concantenated iD.css.
Fix Loading
Fix drawing areas

the way that the vertex is being added to is the original one,
not the one with the 'end' node, so there is no need to remove it.

The new node de-dupe code was making this break area drawing.

Fixes #1322
disable reset button when background not offset

also, only start the fast adjustment after 500ms to
prevent slow clicks from triggering multiple nudges

fixes #1312
d3.xml for status so that it works without auth
Don't hard-code "view on openstreetmap.org" URL

Fixes #1325
fix id in intro, fixes #1323
improve navigating saving with keyboard
Update osm-auth
Use Connection#userUrl
Restore source switch for development
Add a preauth method
Fix tests
URL, not Url
Remove context dependency from Connection
Move Connection to core
Clean up how OAuth keys are handled

Connection defaults to osm.org URL and keys for the simple
case. Customization is done via connection.switch().

Externalize SourceSwitch's use of iD.data.keys.
force blur and tag change when closing inspector

Firefox doesn't fire a blur if the element is just
removed from the dom.
make difference calculation stricter

Changed entities with the exact same properties no longer get counted as
modified.

issue #1287
Allow suggested maxspeed units to be overridden

fixes #947