* scm/framework-ps.scm (write-preamble): use (NAME . CONTENTS) and

* scm/framework-ps.scm (write-preamble): use (NAME . CONTENTS) and
(NAME . FILE-NAME) tuples for font descriptions.
(write-preamble): display BeginFont DSC comments.

* python/fontextract.py (write_extracted_fonts): new file. Extract
font resources from a PS file.

* scripts/lilypond-book.py (option_definitions): --psfonts option.
(Compile_error.process_include): do_file returns chunks.

* make/ly-vars.make (DVIPS_FLAGS): don't load .map file.

* make/lysdoc-targets.make: .texi is .PRECIOUS

* scripts/lilypond-book.py (write_if_updated): new function.