[generator] Improve logging

- more logging for various stages start/finish
- silenced some too repetitive and common warnings (changed to LDEBUG)

Signed-off-by: Konstantin Pastbin <konstantin.pastbin@gmail.com>

generator/final_processor_complex.cpp

@@ -63,6 +63,8 @@ void ComplexFinalProcessor::UseBuildingPartsInfo(std::string const & filename)
 
 void ComplexFinalProcessor::Process()
 {
+  LOG(LINFO, ("Processing complex features..."));
+
   if (!m_buildingPartsFilename.empty())
     m_buildingToParts = std::make_unique<BuildingToBuildingPartsMap>(m_buildingPartsFilename);