first try of keeping connections alive in QHttpClient.
addHeaderValue<>() has been added to QHttpAbstractOutput.
add nodejs/server-ka.js as a test server.
add example/client-keep/ sub project to source tree.
simplify qhttpbase.hpp classes to cleaner API.
update client::QHttpRequest implementation to new qhttbase.
update qhttpbase.hpp to support reader, writer and parser objets.
update client::QHttpRequest to new qhttpbase.hpp
update client::QHttpResponse to new qhttpbase.hpp
update and rewrite client::QHttpClient with new qhttpbase.hpp
update example/client-ka/ to accept local and tcp option from cmd line.
update all *.pro files to use dynamic library of qhttp.
path of UNIX socket can be passed by command line to benchmark app.
add collectData() to HttpReader class.

fix a bug in TImpl static_casting.
remove allBytesWritten() method from client::QHttpRequestPrivate.
update QHttpClient to close the connection automatically when needed.
update server::QHttpRequest with new qhttpbase.hpp
update server::QHttpResponse with new qhttpbase.hpp
rewrite server::QHttpConnection with new qhttpbase.hpp.
update example/client-keep to accept UNIX socket path from cmd line.

also catchUnixSignals has been added.