The true value is case-insensitive.

Boost needs a long in host order.

This avoid undefined behavior on destruction (i.e. ASan's
new-delete-type-mismatch).

The parsing itself is still missing.

To validate which anwers are desired.

Also add Apache 2.0 license (missing from its files), and include information
in licenses script.

The only changes are namespace adjustments.

In preparation for moving to header.

In preparation to accept plain readers.

Call them explicitly from `connect_to_origin`.  Take care of not attempting
DoH when resolving a request to the DoH resolver itself, otherwise we get an
exponentially increasing amount of self requests!

Still mimicking requests sent to simple proxy.

(Although connections seemed to already be reused anyway.)

It mimicks (and may need refactoring with) "fetch via simple proxy".  Also use
a reference to the cancel object as the later does.

To encapsulate Ouinet header manipulation in `fetch_*` functions.

Since it may need to be altered (e.g. for client authentication).

None of them implemented yet.