some refactoring

* massive changes inside includes, drop unused definitions
* rewrite some initialization methods to avoid additional
freeing/allocation
* drop some explicit destructors calls

sources/extsysmonsources/weathersource.cpp

@@ -37,8 +37,6 @@ WeatherSource::WeatherSource(QObject *_parent, const QStringList &_args)
 WeatherSource::~WeatherSource()
 {
     qCDebug(LOG_ESS) << __PRETTY_FUNCTION__;
-
-    delete m_extWeather;
 }