add cloneArgs option to td.when/td.verify

This means that if an arg is mutated, users will see the real one for
recorded invocation. 

Fixes testdouble#375

This config option makes it possible to stub & verify values that are 
mutated at some point by checking whether args match by value as opposed
to reference

Fixes testdouble#416

…/testdouble.js into lgandecki-deeplyNestedProxyObjects

Some imitated functions (esp constructors) will have child props that
are themselves test doubles, so we should recursively print their 
children, too

After reading the spec, I came to a different opinion about how objects
should be handled. In particular, it seems to me that printing deeply
nested children under a `children` property, while still having the 
top-level object "quack" like anything else passed to `td.explain()`
seemed like the best balance of new information with 
compatibility/consistency.

Relatedly, the attempt to uncover deeply-nested items would require way
too much edge-case handling for this function to do on its own (see
the implementation of td.imitate() for how many dragons are involved).
To accomplish a recursive clone, this change pulls in _.cloneDeepWith
and passes a transformer func for the case that a function is visited.
Test double functions are explained and non test double functions are
given a null descriptor where isTestDouble returns false.

I changed the tests to express all this in the minimum number of test
cases while maximally asserting everything that is returned by 
`td.explain`.

Just trying to understand what this is doing. A command pattern seemed
not helpful

…js into robwold-explain-object

…pendency

Remove unnecessary dependency on es6-map.

docs: Correct broken link to testdouble-qunit

…ry __mocks__ scratchpad