BasicEffect warnings on Tier 1 hardware when not using texturing

[walbourn]

When using the model tutorial, you get the following error on Tier hardware (such as the Surface Pro 3)

D3D12 ERROR: ID3D12CommandList::DrawIndexedInstanced: Root Parameter Index [0] is not set. On a Resource Binding Tier 1 hardware, all descriptor tables declared in the currently set Root Signature (0x000001BE6A00C0B0:'Unnamed ID3D12RootSignature Object') must be populated, even if the shaders do not need the descriptor. [ EXECUTION ERROR #991: COMMAND_LIST_DESCRIPTOR_TABLE_NOT_SET]

D3D12: **BREAK** enabled for the previous message, which was: [ ERROR EXECUTION #991: COMMAND_LIST_DESCRIPTOR_TABLE_NOT_SET ]

[walbourn]

The fix here requires a different root signature when using non-textured versions of BasicEffect.

[walbourn]

• BasicEffect root signature split into MainRS and NoTextureRS.
• MainRS parameter order changed, updated AlphaTest and Skinning effects

[walbourn]

Fix submitted.