Neomutt: adds better support for multipart emails

Neomutt now supports sending multipart emails better. See details in my
blog:

https://jonathanh.co.uk/blog/multipart-emails-in-neomutt/

bin/.bin/emails/convert-multipart

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+# https://github.com/anufrievroman/Neomutt-File-Picker/blob/master/filepicker
+# https://github.com/neomutt/neomutt/issues/3229
+# https://unix.stackexchange.com/questions/612134/neomutt-run-command-to-attach-file-on-macro-key-press/612194#612194
+
+commandsFile="/tmp/neomutt-commands"
+markdownFile="/tmp/neomutt-markdown"
+htmlFile="/tmp/neomutt.html"
+
+cat - > "${markdownFile}.orig"
+echo -n "push " > "$commandsFile"
+
+cp "${markdownFile}.orig" "$markdownFile" 
+
+grep -Eo '!\[[^]]*\]\([^)]+' "$markdownFile" | cut -d '(' -f 2 |
+	grep -Ev '^(cid:|https?://)' | while read file; do
+		id="cid:$(md5sum "$file" | cut -d ' ' -f 1 )"
+		sed -i "s#$file#$id#g" "$markdownFile"
+	done
+
+if [ "$(grep -Eo '!\[[^]]*\]\([^)]+' "$markdownFile" | cut -d '(' -f 2  | grep '^cid:' | wc -l)" -gt 0 ]; then
+	echo -n "<attach-file>\"$markdownFile\"<enter><toggle-disposition><toggle-unlink><first-entry><detach-file>" >> "$commandsFile"
+fi
+
+
+pandoc -f markdown -t html5 --standalone --template ~/.pandoc/templates/email.html "$markdownFile" > "$htmlFile"
+
+# Attach the html file
+echo -n "<attach-file>\"$htmlFile\"<enter>" >> "$commandsFile"
+
+# Set it as inline
+echo -n "<toggle-disposition>" >> "$commandsFile"
+
+# Tell neomutt to delete it after sending
+echo -n "<toggle-unlink>" >> "$commandsFile"
+
+# Select both the html and markdown files
+echo -n "<tag-entry><previous-entry><tag-entry>" >> "$commandsFile"
+
+# Group the selected messages as alternatives
+echo -n "<group-alternatives>" >> "$commandsFile"
+
+
+
+grep -Eo '!\[[^]]*\]\([^)]+' "${markdownFile}.orig" | cut -d '(' -f 2 |
+	grep -Ev '^(cid:|https?://)' | while read file; do
+	id="$(md5sum "$file" | cut -d ' ' -f 1 )"
+	echo -n "<attach-file>\"$file\"<enter>" >> "$commandsFile"
+	echo -n "<toggle-disposition>" >> "$commandsFile"
+	echo -n "<edit-content-id>^u\"$id\"<enter>" >> "$commandsFile"
+	echo -n "<tag-entry>" >> "$commandsFile"
+done
+
+
+if [ "$(grep -Eo '!\[[^]]*\]\([^)]+' "$markdownFile" | cut -d '(' -f 2 | grep '^cid:' |
+	wc -l)" -gt 0 ]; then
+	echo -n "<first-entry><tag-entry><group-related>" >> "$commandsFile"
+fi