Updates Tool & Manual on PA DEP input; Tab consolidation

From Barry Evans:
- Fix "Urban Area" section of "Total Load Reductions" tab, to return "--" if Urban Area (and their loads) are zero.
From me: Tab consolidation and formating updates
- Resolve #8 Combine "Stream Bank Loading Rate" tabs for Sediment, Nitrogen & Phosphorus
- Resolve #7 Create "Technical Documentation" tab, expanding from "Perf Std Approach"
- Improved number formatting in "Total Load Reductions" tab, adding commas to the big numbers and percent symbols to the percentages.
- Renamed some tabs for consistencey and added minor formatting changes to improve consistency amongst the tabs