GUILE 2.2 progress

[Han-Wen Nienhuys]

See https://github.com/hanwen/lilypond/pull/1

This has a stack of dependent commits (see below). I don't know how to
deal with this on Rietveld.

commit 3c8081d25b53529efe687ffe9e92ef48f5d11ea2
Author: Han-Wen Nienhuys <address@hidden>
Date:   Sun Jan 26 12:19:56 2020 +0100

    Parse inline scheme using Overlay_string_port

    Overlay_string_port makes a port view of the existing data. This port
    is used for parsing the embedded Scheme form, and is then discarded.

    The port view uses UTF-8 encoding, so UTF-8 encoded string constants
    within the Scheme constants are interpreted as Unicode correctly.

    This obviates the string port that Source_file carries along.

commit ab765369321a0fc9256b78b74ef98c23ba7498f3
Author: Han-Wen Nienhuys <address@hidden>
Date:   Sun Jan 26 12:19:49 2020 +0100

    Overlay_string_port

commit 9188f7f65992fc8768402cfec3ec55a8c2adabd2
Author: Han-Wen Nienhuys <address@hidden>
Date:   Sun Jan 26 11:16:43 2020 +0100

    Clean up embedded scheme parsing/evaluation.

    Renames and reorders functions to clarify the mechanism. No functional
    changes.

-- 
Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen