Charting update

So, I accidentally committed plugin 106 with this as well (though no real changes)...whoops.

Anyway, the basic code behind the charting display type. I expect there will be possible bugs feature requests, but until we get plugins that use the functionality this should be fairly minor.

Changes to default Style to define chart colours and size.

Added charting functions to vCheck.ps1 and support for new $Display value.

Started a wiki page here for information: https://github.com/Sneddo/vCheck-vSphere/wiki/Using-Graphs-in-your-plugin