fix #505, be smarter at getting the letters at fastscroller

app/src/main/kotlin/com/simplemobiletools/contacts/pro/fragments/MyViewPagerFragment.kt

@@ -243,7 +243,17 @@ abstract class MyViewPagerFragment(context: Context, attributeSet: AttributeSet)
     private fun setupLetterFastscroller(contacts: ArrayList<Contact>) {
         letter_fastscroller.setupWithRecyclerView(fragment_list, { position ->
             try {
-                val name = contacts[position].getNameToDisplay()
+                val contact = contacts[position]
+                var name = when {
+                    contact.isABusinessContact() -> contact.getFullCompany()
+                    config.startNameWithSurname -> contact.surname
+                    else -> contact.firstName
+                }
+
+                if (name.isEmpty() && contact.emails.isNotEmpty()) {
+                    name = contact.emails.first().value
+                }
+
                 var character = if (name.isNotEmpty()) name.substring(0, 1) else ""
                 if (!character.areLettersOnly()) {
                     character = "#"