New issue: run time eager module loading

[David M. Lloyd]

It looks as though the instantiation of a Layer causes a complete load 
of all the modules in the layer.  Apart from the consequent lack of 
dynamicism, I think this is very likely to cause problems for large 
applications, particularly if such an application might have many 
operation modes, some of which do not require *all* of the bundled 
modules to be loaded every single time.

Can there not instead be an incremental resolution algorithm, akin to 
how classes are lazily loaded?
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- DML