support Strided convolution conv3d2d

Is this line the only difference with conv3d()? If so, it isn't good to have so much code duplication. You can easily remove code duplication that way:

add a parameter type="conv" to conv3d().
Modify conv3d() such that when type == conv, you do the old behavior. When type=corr, you do the new behavior. Else, raise an error.

make corr3d() call conv3d with type=corr.