Add a help entry and documentation for @ character (bug #52771). expr.txi: Add sub-node "Access via Handle" to the "Calling Functions" node. Don't indent a paragraph that refers to the previous example. Provide the body for the "Access via Handle" node and include an '@' opindex entry qualified by "function handle". Mention that '@' is also used for class methods and reference the "Object Oriented Programming" chapter. oop.txi: Add an opindex reference to '@' qualified by "class methods" so a quick index link is created. op-kw-docs: Create an operator index entry for '@'. Mention that '@' is also used for class methods and suggest seeing the "Object Oriented Programming" chapter of the manual. octave.texi: Add sub-node "Access via Handle" to sub-menu list.

--- a/doc/interpreter/octave.texi	Wed Jan 03 22:30:54 2018 -0800
+++ b/doc/interpreter/octave.texi	Tue Jan 02 15:29:10 2018 -0600
@@ -359,6 +359,7 @@
 
 * Call by Value::
 * Recursion::
+* Access via Handle::
 
 Boolean Expressions