Issue #41. Tidied up sorting code a little.
Tidied up global path definitions.
Updated docs with svgweb info.
Issue #45. Added svgweb files to the repository.
Issue #45. Implemented IE 8 compatibility for graph display. Untested.

Also bumped the X-UA-Compatible header to use IE 9 where available,
since the SVG shim is a bit laggy with a large SVG file and if IE 9
isn't available, the next highest version will be used (IE 8).
Issue #41. Overlaps can no longer cause cycle-forming edges.

Also fixed plugins with the same size not being detected. Not sure about
how the edge formation changes affect the sorting validity, haven't
checked yet.
Issue #41. Fixed priority data not being used to create edges in graph.
Documented the required GraphVis binaries.
Fixed issue #48.
Fixed issue #46.
Issue #45. Graph generation is now disabled by default.
Updated libespm usage to reflect library changes.
Fixed issue #49.