example: exlude keepalive pro when client is ruled out

update README and bump to version 3.0

update README.md and add `unsupported` to SSL backend.

tweak for ./update-dependencies.sh

new file name convention to project source tree.

* server class files are start with qhttpserver prefix.
* some better doxygen comments.
* a unique convention for #ifndef of each *.hpp file.
* remove Windows dllexport/dllimport directive.
* show a warning for Windows compilation.
* show an error if Qt < 5.0.0
* remove all license headers!

QHttpConnection: public QTcpSocket, add Q_DECLARE_PRIVATE.

change other sources to comply.

fix problems on example/httpclient-raw.

change direct call of start() as a slot to QMetaObject::invokeMethod.

change write() to end() in ClientConnection.

add example/basic-server project.