Regarding documentation, comments in tens of .h files in third level directories are very user unfriendly, regardless of their quality (which seems fairly good)

Regarding documentation, comments in tens of .h files in third level directories are very user unfriendly, regardless of their quality (which seems fairly good). You need: 1) an overview of the available functionality, design choices, aspects that need feedback and contributions etc. 2) a guide of what headers every function or macro is located in (consider fragmenting headers less, possibly adding "umbrella" headers that just include a set of the current headers that is likely to be used together) 3) generated API docs in the web site.