Centre and prevent scrolling

Centres the map and prevents scrolling beyond the bounds of the map
Added seperate script for loading the svg

Enough witht the shit of mediawiki rendering out orphan <p> tags within
my JS.
Convert plasmidScript code into a function to run with passed in parameters
Fixed a bug in plasmidScript.js

was appending innerdiv to div although it was already appended. This
resulted in a HIERARCHY_REQUEST_ERR: DOM Exception 3.
Also changed url from a remote one to a relative one.
Finally works the way we wanted it to.

Cut out the whitespace and scrolls well.