Infer beta changelog for TestFlight

Pick changes from latest release.

ci/commit-beta-changelog.sh

@@ -8,3 +8,5 @@ sed "s/Unreleased/$VERSION Beta $BUILD ($DATE)/" $TARGET >$TARGET.tmp
 mv $TARGET.tmp $TARGET
 git add $TARGET
 git commit -m "Set beta release"
+
+ci/latest-changelog.sh >ci/$TARGET

ci/latest-changelog.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+TARGET="CHANGELOG.md"
+RELEASES=(`grep -n "^## " $TARGET | sed -E "s/^([0-9]+).*$/\1/g"`)
+UNRELEASED=${RELEASES[0]}
+LATEST=${RELEASES[1]}
+cat $TARGET | head -n $((LATEST - 1)) | tail -n $((LATEST - UNRELEASED - 2))