This is an adapted PR of #7594

Templates use the $this->countModules('myposition') to determine whether or not to show a position (and surrounding html).
However, when a module is empty (no content), the countModules is not affected.
This can result in positions being shown with no modules in it.

This PR adds the option to not include empty modules in that count.
This can be done by adding false as second argument (setting $include_empty to false):
$this->countModules('myposition', false)

Testing Instructions

Easiest way to test with an empty module is to use Advanced Module Manager, as that will make the content truly empty even if the module has an empty <p></p> tag.
So just make a Custom HTML Module and leave the content area empty. Assign it to a module position (that has no other modules assigned to it). Like manually entering testempty in the module position field. And switch on the 'Hide if Empty' option.

Or create your own module that returns an empty content.

Then in your template place this somewhere:

<?php
echo "\n\n<pre>==========================\n";
echo 'Real module count for position "testempty": ' . $this->countModules('testempty');
echo "\n==========================\n";
echo 'Not-empty module count for position "testempty": ' . $this->countModules('testempty', false);
echo "\n==========================</pre>\n\n";
?>

Opinion

In my opinion the default for $include_empty should be false.
As people are saying in #7594 that would change behaviour. That is true, but I believe it only changes it in edge cases and only when those edge cases don't want the empty modules to be counted.
However, that isn't worth my time to fight for, so hope this 'addition' instead of a 'fix' does get accepted.
Then it is up to the template developers to implement it.