Function: write_set_file

DOC_MSE_VERSION: since 0.3.8

--Usage--
> write_set_file(set:the_set, file: filename)

Write the current set to a file in the output directory.
If a file with the given name already exists it is overwritten.

Returns the name of the file written.

This function can only be used in an [[type:export template]], when <tt>create directory</tt> is true.

--Parameters--
! Parameter	Type			Description
| @set@		[[type:set]]		Set to write to the file.
| @file@	[[type:string]]		Name of the file to write to

--Examples--
> write_set_file(file:"the-set.mse-set") == "the-set.mse-set" # the-set.mse-set now contains the set

--See also--
| [[fun:write_image_file]]	Write an image file to the output directory.
| [[fun:write_text_file]]	Write a text file to the output directory.
