Get rid of debug messages and fix superclass constructor calls.
Turn on -Werror in CXXFLAGS, and fix a few warnings.
Add a handler type for path+msg.
Add a Blob class.
Add a Message constructor that allows adding arguments.

This allows expressing message construction and sending in one-liner!
Add a Bundle class.
Add an ownership flag to Message.
Add a function to send a no-arg message.
Add a wrapper for lo_message_pp().
Use the Message class in handlers instead of lo_message.
Implement method deletion.

Required changing the vector used to store handler wrapper functions
into an unordered map of lists indexed by the path and typespec of the
method.
Enforce ownership semantics statically by a bool template for Message and Bundle.

For instance, the compiler can now verify that Bundle only takes
ownership over messages that do not have ownership.  Otherwise
double-frees can easily occur when constructing temporary Messages on
the stack and passing them into Bundles.

It would be better to have a concept of ownership *transfer*, like
std::unique_ptr.

The syntax is not as clean due to this template argument, but forcing
the user to think about ownership is probably overall a good thing,
since it can easily lead to leaks and crashes.