Discover North America v1.4 Mod

Changes 1.4 ATS 1.51 (Arkansas compatible Release.) -Pitt Fixes, Skyline improvements -Boston Improvements, and Fixes (Matt) -Providence, RI Skyline WIP implemented (layout being reworked) -Manitoba work begun (hidden roads one slipped through v1.3.5 will have roads and a Boilerplate layout of Winnipeg.) -More Toronto replacements in skyline, new companies coming.