Added tree-view context menu options 'Open File' and 'Open File Location'.
Added IProjectItem.OriginalPath.
- For PipelineProject this replaces FullPath
- For ContentItem this replaces SourceFile
- For FolderItem this is identical to Location
Added IController.GetFullPath(string) which returns the an absolute path given a project relative path (or returns unchanged path if already rooted).
Double clicking on a ContentItem will now 'Open File'.
Fixing typo, inverted conditional.
Merge branch 'PipelineToolOpenFile' into PipelineTool_OpenProject_CommandLine

Conflicts:
	Tools/Pipeline/Windows/MainView.Designer.cs
	Tools/Pipeline/Windows/MainView.cs