dev
fix copyright years
Harden TDNF build by enforcing various GCC build flags
plugin headers and initial repogpgcheck plugin implementation - plugin event map for guidance to event items - plugin events init, repo, repomd - tests for plugin conf - tests with a repomd sign and verify via plugin
Remove duplicate code (#136)
Fixed TDNFDownloadFile call in repogpgcheck plugin
Add helper script to build tdnf using llvm (#448)