0.0.7 with Sloped modes

This version includes several large additions, including two modes that add smoother-looking sloped voxels to the model as it renders it, changes to colors, changes to the double-size renders to reduce jagged edges, and extra sizes of ortho renders with varying degrees of smoothing/rounding applied. A Usage.txt file was added with instructions to the download, and the default model (if unspecified) is now Zombie.vox because it shows the slopes off a little better. Most importantly, drag and drop works now, so you can drag a .vox file onto IsoVoxel.exe and it will render it in a subfolder.