Record the new Best in the spec and the manual

denoise.md §15: why Best became one network, how it compares with the
mixture and Medium on real photographs and the chart, the candidates that
fell short, the file names, the saved-edit numbering, and the timings on
the 3050 -- 0.51-0.54 s whole-frame, 0.95 s in tiles, against 2.60 s for
the mixture in tiles. The manual lists Bilinear, Fast and Best, says an
edit made with Medium opens with Best, and gives the new time; Medium's
close-up goes.

docs/manual/index.html

@@ -296,22 +296,21 @@ colour that come with it, while keeping the fine detail. Look at it at
 1:1, where noise lives.</p>
 <p><code>Method</code> chooses how:</p>
 <ul>
-<li><code>Best</code>, the default: two networks, one for smooth areas and one for
-edges, blended where each is better. The cleanest skies and the sharpest
-lettering, and the slowest.</li>
-<li><code>Medium</code>: one network taught by <code>Best</code>. Nearly as clean in smooth areas,
-a little softer on hard edges, in about a third of the time.</li>
-<li><code>Fast</code>: a smaller one, taught the same way. Visibly noisier at very high
-ISO than the other two, but still far cleaner than none, and quick.</li>
+<li><code>Best</code>, the default: clean skies and sharp lettering, edges kept as
+crisp as the camera recorded them.</li>
+<li><code>Fast</code>: a smaller network, taught the same way. Visibly noisier at very
+high ISO than <code>Best</code>, but still far cleaner than none, and quicker.</li>
 <li><code>Bilinear</code>: the camera's ordinary conversion, noise and all.</li>
 </ul>
+<p>A photograph last edited with <code>Medium</code>, which earlier versions offered,
+opens with <code>Best</code>.</p>
 <p>The photograph shows the camera's ordinary conversion while the network
 works, with its progress in the bar at the top, and changes when it is
-done — on a laptop's graphics card, about two and a half seconds for a
-20-megapixel photograph with <code>Best</code> and under one with the other two;
-longer on a processor alone or on the tablet. The first photograph after
-installing waits a few minutes more while the graphics card prepares each
-network, once. The result is kept, so a photograph opened again,
+done — on a laptop's graphics card, about a second for a 20-megapixel
+photograph with <code>Best</code>, reading the file included; longer on a processor
+alone or on the tablet. After installing, the graphics card spends up to a
+quarter of an hour preparing each network, once, in the background; the
+photographs developed meanwhile take a little longer. The result is kept, so a photograph opened again,
 or exported, does not wait a second time, and switching back to a method
 already used is quick.
 <code>Strength</code> eases it off: below 100 % it puts back some of what was removed,
@@ -319,8 +318,8 @@ as grain without colour, for a picture that does not look too smooth.</p>
 <p>The lamp and railing of a night frame at ISO 8000, at 1:1, by each method:</p>
 <table><thead><tr><th>Bilinear</th><th>Fast</th></tr></thead><tbody>
 <tr><td><img src="media/develop-denoise-bilinear.png" alt="The railing and the lamp at ISO 8000, as the camera recorded them" /></td><td><img src="media/develop-denoise-fast.png" alt="The same, with the Fast network" /></td></tr>
-<tr><td><strong>Medium</strong></td><td><strong>Best</strong></td></tr>
-<tr><td><img src="media/develop-denoise-medium.png" alt="The same, with the Medium network" /></td><td><img src="media/develop-denoise-best.png" alt="The same, with the Best network" /></td></tr>
+<tr><td><strong>Best</strong></td><td></td></tr>
+<tr><td><img src="media/develop-denoise-best.png" alt="The same, with the Best network" /></td><td></td></tr>
 </tbody></table>
 <p>It works on raw files from any camera with the usual colour pattern of
 red, green and blue squares — not on JPEGs, and not yet on Fujifilm's