Anything that uses Qt5 should probably be using the qt5 or qmake5 portgroup. Qt dependencies are then expressed not by using depends_build or depends_lib but by using qt5.depends_component or qt5.depends_build_component.
Anything that uses cmake should be using the cmake portgroup. This takes care of the cmake dependency and typical flags.
Anything hosted on github should be using the github portgroup. This takes care of homepage, master_sites, livecheck, extraction.
The license field is a space-separated list of licenses; "Modified" is not the name of a valid license. Setting the license correctly is necessary so MacPorts can determine if a port's binary is distributable. It looks like in this case the specific modified BSD license being used is known more commonly as the 3-clause BSD license. In MacPorts, we refer to the 3-clause and 2-clause BSD licenses simply as "BSD".
An empty maintainers line is not valid. Put your obfuscated (host:user) email address if you wish to maintain it, or "nomaintainer" if you do not.
