Document and release 4.2.0-1pureos1~byz

Backport from !5 (merged)

Fixes #8

Could you remove the optimizations from "Default preferences for Debian"? Those go pretty far with how they reconfigure the engine and I don't think we should touch those things by default.

So, do you mean all the things from https://source.puri.sm/Librem5/debs/firefox-esr-mobile-config/-/blob/rel_byz_4.2.0/debian/patches/0001-mobile-config-autoconfig-add-Mobian-preferences.patch ? (I've not tried without uidensity btw)

or "just" the following:

+    // Firefox is optimized for desktop.
+    // Some desktop optimizations might slow things on mobile.
+    // We should especially reduce CPU and RAM usage.
+
+    // Reduce the number of content processes.
+    //
+    // The more content processes you have,
+    // the more CPU and RAM will be assigned to each tab.
+    //
+    // Source: https://bit.ly/3dc4A7W
+    // Default value: 4
+    // Goal: Save CPU and RAM.
+    defaultPref("dom.ipc.processCount", 1);
+
+    // Disable prefetching.
+    //
+    // Source: https://bit.ly/3dc4A7W
+    // Default value: true
+    // Goal: Save bandwith
+    defaultPref("network.prefetch-next", false);
+
+    // Limit content redraws.
+    //
+    // While this helps the browser feel snappy,
+    // frequent redraws increase the total page load time,
+    // so a longer content notify interval will improve performance.
+    //
+    // Source: https://bit.ly/3hLX47p
+    // Default value: 120000 (0.12s) / true
+    // Goal: Speed up page loading
+    defaultPref("content.notify.interval", 500000);
+    defaultPref("content.notify.ontimer", true);
+
+    // Reduce the content switch threshold.
+    //
+    // If you haven't moved your mouse or touched the keyboard for the given time
+    // (the content switch threshold) then Firefox enters a low frequency interrupt mode,
+    // which means its interface becomes less responsive but your page loads more quickly.
+    //
+    // Source: https://bit.ly/3hLX47p
+    // Default value: 750000 (0.75s)
+    // Goal: Speed up page loading
+    defaultPref("content.switch.threshold", 250000);
+
+    // Reduce the number of visited web pages stored in memory,
+    // which you can access using the Back and Forward buttons.
+    //
+    // Source: https://bit.ly/3dc4A7W
+    // Default value: -1 (adaptable)
+    // Goal: Save RAM
+    defaultPref("browser.sessionhistory.max_total_viewers", 1);

Generally I think we shouldn't have anything that isn't about fitting the UI on a small screen there, at least unless there's a very strong reason to have it.

mentioned in issue #10

Currently in byzantium the firefox-esr (128.3.1esr-1~deb11u1) raises an error when starts with firefox-esr-mobile-config (3.0.0-1pureos1) but this merge request solve it.

See also:

• https://forums.puri.sm/t/firefox-esr-after-update-failed-to-read-config-file/26595
• https://forums.puri.sm/t/firefox-new-error/26699

merged manually