Fix cargo loading/unloading.

- Fix the unloading subcell bug, letting us have units move to directly adjacent cells.
- Have the cursor change to a deploy-blocked cursor if the transport can't unload due to terrain type.
- Add RenderTransport for transport door opening.
- Remove turning/opening in general.

OpenRA.Mods.RA/OpenRA.Mods.RA.csproj

@@ -333,6 +333,7 @@
     <Compile Include="Render\RenderInfantry.cs" />
     <Compile Include="Render\RenderInfantryPanic.cs" />
     <Compile Include="Render\RenderSpy.cs" />
+    <Compile Include="Render\RenderLandingCraft.cs" />
     <Compile Include="Render\RenderUnit.cs" />
     <Compile Include="Render\RenderUnitReload.cs" />
     <Compile Include="Render\WithBuildingExplosion.cs" />