Improve Shadow Mapping

[MarkOates]

Premise

Soon shadow mapping will be available/integrated as a part of AllegroFlare, but this current implementation of shadow mapping suffers from some common visual flaws. Here is a great article providing tips on improving shadow mapping appearance and processing:

https://docs.microsoft.com/en-us/windows/win32/dxtecharts/common-techniques-to-improve-shadow-depth-maps