Fix saving intraline highlight diff preference

The server returns boolean false values as missing
properties. DiffPreferences needs to assume a boolean
is false if the property is not defined.

Change-Id: Ibd32fd6fc4743a0d06d2e86715a4a1f2e49d05ca
Fix: 'Send' can work before the comments preview is loaded.

In the reply box of ChangeScreen2, the comments are loaded
and show in a preview under the cover message box.

If the user presses "Send" before the comments preview
is loaded, it does not react.

Fixed. Disable Send button until comments preview has loaded.

Bug: issue 2307
Change-Id: I905bffa15593eaf8757d8ec8c2972aff94e38d90
Rename Documentation link 'Index' to 'Table of Contents'

Change-Id: If7040f7b89d2a4b2947d40385e370d0201a65596
Merge "Rename Documentation link 'Index' to 'Table of Contents'"