Removed two clock functions which were alwaysProgressing time based off epoc
Instead we just use the two functions which are based off the Clock startup time (which have been renamed).
There is little to no value having an always progressing time which is based off epoc.  If you need an absolute time, it's better to rely on the system clock.
This makes it so that you can't reference how the system clock has changed over time, and have an epoc reference which is always progressing, but I can't think of a condition where either of those would be useful (someone please file an issue if those are interesting to you).  The goal of this is to simplify the library, reduce unused code, and to make it more obvious when you use one version compared to the other (and the fact that the two methods are NOT compatible).