after we split the solution into multiple projects the xml doc comments were no longer packed in the generated nuget package. in addition they were only generated for the net standard 2.0 target framework.
this change generates comments for all target frameworks and makes sure they're included in the generated package. it also adds missing doc comments where they weren't included on the public api and clears up a couple of minor formatting issues in the affected files.
by default nuget pack does not include project dependencies. this is suboptimal since it would require managing at least 5 nuget packages. this uses a workaround detailed here https://github.com/nuget/home/issues/3891 to copy the dependent dlls to the generated nuget package. this doesn't resolve the issue of how we publish the documentlayoutanalysis project, since it is the top of the dependency tree and we publish its parent, rather than it.
to make the project more useful and expose more usable classes we're rearchitecting in the following way. code used to read fonts from external file formats like truetype, adobe font metrics (afm) and adobe type 1 fonts are moving to a new project which doesn't reference most of the pdf logic. the shared logic is moving to a new flat-structured project called core. this is a sort-of onion type architecture, with core being the... core, fonts being the next layer of the onion, pdfpig itself the next. this will then support additional libraries/projects as outer layers of the onion as well as releasing standalone version of the font library as pdfbox does with fontbox.
