Clarify the points at which clinic booking subjourneys move onto the next child

Changes in this commit include:
 - confirmation button text of "Continue to next child" when entering the final detail of the previous child
 - change of title to mention "your next child" when entering chiuld details for 2nd and subsequent children

Also got rid of some old, unused entries in en.js.

Author: malross

app/locales/en.js

@@ -287,7 +287,10 @@ export const en = {
       caption: 'Appointment for %s'
     },
     child: {
-      title: 'What is your child’s name?',
+      title: {
+        first: 'What is your child’s name?',
+        next: 'What is your next child’s name?'
+      },
       caption: 'Appointment for your %s child',
       summary: 'About your child',
       description:
@@ -299,17 +302,6 @@ export const en = {
       lastName: {
         label: 'Last name',
         hint: 'Or family name'
-      },
-      hasPreferredName: {
-        label: 'Do they use a different name in school?',
-        yes: 'Yes',
-        no: 'No'
-      },
-      preferredFirstName: {
-        label: 'Preferred first name'
-      },
-      preferredLastName: {
-        label: 'Preferred last name'
       }
     },
     dob: {

app/views/book-into-a-clinic/form/adjustments.njk

@@ -1,6 +1,9 @@
 {% extends "_layouts/form.njk" %}
 
 {% set title = __("consent.child.adjustments.title") %}
+{% if childCount > 1 and childNumber < childCount %}
+  {% set confirmButtonText = __("clinicBooking.nextChildButtonText") %}
+{% endif %}
 
 {% block form %}
   {{ checkboxes({

app/views/book-into-a-clinic/form/appointment-time.njk

@@ -1,11 +1,14 @@
 {% extends "_layouts/form.njk" %}
 
 {% set title = __("clinicBooking.time.title", firstName) %}
+{% if childCount > 1 and childNumber < childCount %}
+  {% set confirmButtonText = __("clinicBooking.nextChildButtonText") %}
+{% endif %}
 
 {% block form %}
   {{ appHeading({
     title: title,
-    caption: __("clinicBooking.appointment.caption", fullName) if transaction.childCount > 1
+    caption: __("clinicBooking.appointment.caption", fullName) if childCount > 1
   }) }}
 
   {#

app/views/book-into-a-clinic/form/child.njk

@@ -1,6 +1,10 @@
 {% extends "_layouts/form.njk" %}
 
-{% set title = __("clinicBooking.child.title") %}
+{% if childNumber == 1 %}
+  {% set title = __("clinicBooking.child.title.first") %}
+{% else %}
+  {% set title = __("clinicBooking.child.title.next") %}
+{% endif %}
 
 {% block form %}
   {{ appHeading({