Updates to getPrice to either include or exclude tax

Also redirect to a route rather than the URL (I've wanted to change the URL that the route points at and redirecting to a URL breaks this).
That argument has not stopped nlundsten pushing changes to catalog that cause breaks (big breaks) in BC. Based n that logic we will never be able to break BC which is all kinds of wrong. It also introduces masses of inconsistency between very similar functions (getExtPrice). How do you propose we over come this? I'm not denying this is a break in BC but I believe it is best for the module.