Memory leaks when Channel() constructor throws

[stonemaster]

There are memory leaks when the constructor Channel throws an exception:

• The m_impl->m_connection won't be reset because the object has not been successfully created. So ~Channel() won't ever be called. Maybe m_connection should be wrapped in a thin wrapper which just handles freeing the connetion.
• If an error occurs and amp_error_string is called, the memory which is reserved within that function never gets freed.

[alanxz]

These look like a valid bug. Thanks for reporting!

[alanxz]

Should now be fixed.

[stonemaster]

Thanks for the patch! Works like a charm.