This package is similar to and depends on the ashr package (https://github.com/stephens999/ashr) but also allows the error distribution to be any mixture of normals or uniforms. See that link for details on the model.
Right now, I would only suggest using a mixture of normals as your error distribution. The mixture of uniforms seems to work OK if you have a huge grid, but not well otherwise.
To install, run the following code in R
install.packages("devtools")
devtools::install_github("dcgerard/stramash")