Added sub/superscript to composer

app/src/main/java/eu/faircode/email/SuperscriptSpanEx.java

@@ -0,0 +1,39 @@
+package eu.faircode.email;
+
+/*
+    This file is part of FairEmail.
+
+    FairEmail is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    FairEmail is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with FairEmail.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2018-2022 by Marcel Bokhorst (M66B)
+*/
+
+import android.text.TextPaint;
+import android.text.style.SuperscriptSpan;
+
+import androidx.annotation.NonNull;
+
+public class SuperscriptSpanEx extends SuperscriptSpan {
+    @Override
+    public void updateDrawState(@NonNull TextPaint textPaint) {
+        super.updateDrawState(textPaint);
+        textPaint.setTextSize(textPaint.getTextSize() * HtmlHelper.FONT_SMALL);
+    }
+
+    @Override
+    public void updateMeasureState(@NonNull TextPaint textPaint) {
+        super.updateMeasureState(textPaint);
+        textPaint.setTextSize(textPaint.getTextSize() * HtmlHelper.FONT_SMALL);
+    }
+}