Update app and module versions for 4.19.0

Core/manifest.mf

Core/nbproject/project.properties

Experimental/nbproject/project.xml

ImageGallery/nbproject/project.xml

KeywordSearch/manifest.mf

KeywordSearch/nbproject/project.xml

RecentActivity/manifest.mf

RecentActivity/nbproject/project.xml

Testing/nbproject/project.xml

docs/doxygen-user/Doxyfile

docs/doxygen/Doxyfile

nbproject/project.properties

thunderbirdparser/nbproject/project.xml