Initial Powershell integration, fleshing out TreeView

-Clarified rules for checking nodes in TreeView. If a parent node is
checked, check all children. If a child is checked, check all parents.
-Introduced script running based on "Tag" parameter for a node. The leaf
nodes, the actual actions to be run, should all have the name of the
script ("sample.ps1") as the Tag. When user clicks "Attempt Fixes"
button, any checked leaf nodes with a tag will run the script specified
in the tag. Scripts will all run serially, not in parallel!
-Added BackgroundWorker to kick off scripts so the UI doesn't
hang/freeze while they're running.
-Script directory is currently a hard-coded variable to the project
folder on my own machine. This will be changed in time for any release
builds. Still need to finalize location.
-.ps1 scripts right now: MSPaint.ps1 is a sanity script, just to make
sure the integration into .NET is working. ResetWinsockStack.ps1 is a
dummy/sanity script, to make sure running multiple scripts serially is
working.