Updates to posts, comment policy

For clarity, I revised some grammar and added sentences to many posts. In particular I added some explanation to make Determine Pressure Drop in Straight Pipe and Microsoft Visio Guidelines, Tricks, Keyboard Shortcuts easier to read. Nothing factual has changed, so I don’t think you need to re-read them if you understood the first time.

I also added some more info about printing articles and making comments in the about page.