Simplify shared and agency folder layout, rename INI selector to Agency, and update developer guide

.gitignore

@@ -45,16 +45,16 @@ Shared/Server/Source/__history/
 Shared/Server/Source/__recovery/
 Shared/Web/__history/
 Shared/Web/__recovery/
-WC/Web/Win32/
-WC/Web/Win64/
-WC/Web/TMSWeb/
-WC/Web/**/__history/
-WC/Web/**/__recovery/
-BFD/Web/Win32/
-BFD/Web/Win64/
-BFD/Web/TMSWeb/
-BFD/Web/**/__history/
-BFD/Web/**/__recovery/
+Agency Specific/WC/Web/Win32/
+Agency Specific/WC/Web/Win64/
+Agency Specific/WC/Web/TMSWeb/
+Agency Specific/WC/Web/**/__history/
+Agency Specific/WC/Web/**/__recovery/
+Agency Specific/BFD/Web/Win32/
+Agency Specific/BFD/Web/Win64/
+Agency Specific/BFD/Web/TMSWeb/
+Agency Specific/BFD/Web/**/__history/
+Agency Specific/BFD/Web/**/__recovery/
 
 # Runtime libraries already versioned with the server
 !Shared/Server/bin/FastMM_FullDebugMode.dll