provide more control over what goes into module file and how they are composed

[boegel]

This is a feature request made by @rtmclay, and a prerequisite in order to make TACC consider picking up EasyBuild.

• [ ] support providing a plugin to specify a module file template
  • the idea here is to basically provide a dictionary of values + a set of functions to compose a module file with, and let the user define how these should be combined to compose the module file via a Python module
• [ ] provide control over whatis
• [ ] support module families
• [ ] support module properties
• [ ] support prereq vs load

[boegel]

@rtmclay: anything else that comes to mind?

[berndmohr]

provide control over help

[ocaisa]

Add some multi-purpose variables that can be used in random ways (e.g., to add the installer, their email address, a website with detailed usage instructions for this particular system, ascii art,...)