Plugins removed

Plugins are no longer supplied with ICEcoder itself but now available to
install/uninstall remotely
Keep the plugins dir
Plugins removed
Link to plugins manager added
Plugins Manager added

Allows you to install/uninstall as well as update the details of
installed plugins
showManual section and pluginManager function

showManual function can now take a section param and append to iFrame
URL to target a section of the manual if required. Used from Plugin
Manager only for now.
pluginsManager is a new function to display the Plugins Manager on
demand
Added note re setting perms on plugins dir also