Invoke-PipeScript should be more eventful

[StartAutomating]

Invoke-PipeScript should generate a signal whenever a pair of signals whenever a template file is run:

• PipeScript.TemplateFile.Approve should be sent prior to running a TemplateFile #916
• PipeScript.TemplateFile.Out should be sent after a TemplateFile has run (and contain output, errors, and warnings) #917

Invoke-PipeScript should also look for an event denying the execution of a template.

• Invoke-PipeScript should not run a TemplateFile if PipeScript.TemplateFile.Deny is received #918