this removes submodules and external libraries in the code in favor of
importing them as CPM packages. CPM_SOURCE_CACHE is recommended as
codegen has to readd two of the same dependencies
- rename LayerBG.hpp to General.cpp
- add addListBorders UI function for adding comment borders to a list
- change VersionInfo parsing to use streams
- remove VersionInfo::validate and instead just have VersionInfo::parse
- remove scnlib