I have a PR up, 3724, with a first pass at setting up a directory structure both in the source tree and the install tree to enable exporting headers from what is current lib/ts to the install directory so that non-core plugins can use them. If we expect core plugins to server as examples, facilities they use should be also available to non-core plugins. This PR is a demonstration and only provides TextView.h to plugins. If the setup is acceptable I (or others) will move other headers for plugin availability (e.g. BufferWriter, MemArena, MemSpan, ink_inet.h as a first wave). We don't need to get all of these for 8.0 but I would like to get the framework in which they can be moved set up.
I am also looking ahead to being to be do some longer term restructuring to improve code comprehensibility and linking.
