Add TEdit, Sketch, Medley for DOS manuals to the source tree

[pamoroso]

The manuals of TEdit, Sketch, and Medley for DOS are currently stored under the non public folder history-sources > Lisp Library of the shared Google Drive.

To make this valuable documentation publicly accessible it would be useful to copy the manuals to the Medley source tree. For example, the TEdit and Sketch manuals could go in the library/tedit and library/sketch directories of the Medley repo. The Medley for DOS manual could instead go in the DOS repo. In addition, MAN, DInfo, and HCFILES should be adapted to access these additional manuals.

This issue, which we agreed to open in the February 5, 2025 external meeting, addresses and expands on a request for information on how to use TEdit posted by a Mastodon user.

[masinter]

I think some of these may be in the medley bibliography.
Some of these have sources that are already in the source tree in parts.

• There should be a way of running HCFILES where it can combine individual pDFs into one concatenated document. I think this means making a new source file type (.BOOK)? which gets turned into PDF by concatenating the source TEDit files for each chapter, OR using a PDF Toolkit.
• Some of the bibliography entries link to the "pub-pdfs" repository which is not maintained and should go away. Should internal, maintained documents be in the bibliography? If not, remove them. If keeping them, point to the files.interlisp.org copies.