Use the new section title style in Asciidoctor.

We previous use the section title style like:

Section level 1
===============

Section level 2
---------------

Which have a problem in Asciidoctor that the number of "="s or "-"s must match
the number of characters in the header exactly, as a result it's easy to make
mistakes while changing the titles. Asciidoctor provides a better style like:

= Section level 1

== Section level 2

So we switched to this style.

Also fixed a bug in replace_macros.py, which will not cause any problem in the
old style.

Change-Id: I811dd7238735d98f662767c17086152cd69aea02

Documentation/pgm-prolog-shell.txt

@@ -1,31 +1,25 @@
-prolog-shell
-============
+= prolog-shell
 
-NAME
-----
+== NAME
 prolog-shell - Simple interactive Prolog interpreter
 
-SYNOPSIS
---------
+== SYNOPSIS
 --
 'java' -jar gerrit.war 'prolog-shell' [-s FILE.pl ...]
 --
 
-DESCRIPTION
------------
+== DESCRIPTION
 Provides a simple interactive Prolog interpreter for development
 and testing.
 
-OPTIONS
--------
+== OPTIONS
 -s::
 	Dynamically load the Prolog source code at startup,
 	as though the user had entered `['FILE.pl'].` into
 	the interpreter once it was running. This option may
 	be supplied more than once to load multiple files.
 
-EXAMPLES
---------
+== EXAMPLES
 Define a simple predicate and test it:
 
 ====