Archiver Appliance Help & DataBrowser persistence

Added a help page to the archiver appliance plugin, which explains how to set up the appliance in CSS.
Updated the DataBrowser widget to update the selection value PV even if the mouse is not changing, but the data is shifting to the left (or right).
Revised the .plt files, fixed a few bugs and implemented a workaround that enables loading the annotations and show them at the correct spot on the chart (includes one file change in xygraph).