small cleanups
in progress support for wrapping lvalue methods
be a bit more general about sub attributes handled
we always use B, so load it at compile time
test and fix after modifiers with lvalue subs
passing and todo tests for array lvalue methods
add comment explaining +
correct handling of void context
set returned arrays readonly when using after modifiers

It isn't possible to properly pass through an lvalue array without
having it as the final call in a function, which isn't possible when
using an after modifier.  Instead of allowing it to fail silently,
return a readonly array, which will trigger an error.
make sure there are no warnings in tests
document lvalue support
add Test::Warnings dependency
detect lvalue methods without loading B
Merge pull request #4 from haarg/lvalue

Allow wrapping lvalue methods