Add scenario to show issue #27
Replace struct{} with struct{int} for mock types

When we want to make sure that we can tell the difference between
different instances of a type then we need to use struct{int} instead
of just struct{}.

Fixes #27.
Add scenario to show issue #28
Include subdirectories when linking

This appears to fix issue #28 without breaking anything else.  Though
that's probably just because I don't have a test for that yet ... :S
add scenario for issue #29
fix for issue #29
Fix import path
Expand issue #29 scenario to cover return values

Since the parameters weren't working properly, the return values
probably don't either - so expand the scenario to show that too.
Fix exprString for interface methods

We weren't printing names for parameters or returns when they were
specified - which doesn't really matter, except that you can have
multiple names per type when it does matter.  It's also neater to
copy the names used by the original code ...

This helps with issue #29.
Fix interface mock generation

Having got exprString right, we now need to fix interface mock
generation when there are multiple return values using names and the
same type.

Kinda issue #29.
Add scenario to show issue #31
Add missing import to issue #31 scenario

Since the code doesn't compile because of the bug, the compiler
doesn't warn us when imports are missing.
Add scenario to show issue #32
Add scenario to show issue #33
Set fi.varidic for interface methods

When we compile the funcinfo for interface methods we weren't setting
the varidic flag when we should have been.  This meant that the
generated code for interface mocks didn't handle varidic methods
correctly.

This fixes issue #31
Deal with stdlib packages using non-Go code

Many of the standard library packages use non-go code.  In this case
we don't actually care, since we only use generated code when mocking
the package.  So we can replace the external function/method with a
stub and still write a mock for it.  This replaces the special case we
were using for the os package.

Also, fix the issue #33 scenario now that it runs.

This fixes #33.
Remove obsolete function
Add scenario to show issue #34
Ignore init functions for stdlib

When we mock stdlib packages we don't support disabling the mocks - so
don't call the init functions (especially since the init functions may
actually call the stubs we have put in place and cause a panic).

This fixed #34
Add scenario to show issue #35