private loadtheme — function
loadtheme(tree, env)
Searches the given env configuration for a Publish.jl theme and loads it into
the provided tree. Since tree is immutable the updated version is returned
along with a new env containing any merged data from the theme.
loadtheme looks for a publish.theme key in the env and tries to call the
function defined by the value of the key.
The themes included with this package are listed in the Themes module.