Compatibility issue with non-standard arg separator

[CaMer0n]

The following legacy code (dating back to e107 v1) on line 3791 of e107_class.php has compatibility issues with third-party scripts:

self::ini_set('arg_separator.output',     '&');

This "non-standard" setting influences how http_build_query behaves and may cause problems for third-party libraries when they expect the default query parameter to be & because they want to execute a curl request for example.

Throughout the core this value is very often overridden, such as this example on Line 1513 of install.php:

$base = base64_encode(http_build_query($data, null, '&')); 

In many cases class2.php will simply be included prior to the third-party script in order to load user data or prefs. In such a case these scripts may throw errors due to this setting. e107 is not alone in this scenario as you can see here: owncloud/core#14782

For this reason, I'm going to disable this line, reverting to its default '&' value.

If developers require an & (such as when building links for html) then please set it manually as per the following example:

 http_build_query($data, null, '&'); 

I'll be doing the same in the core where it is necessary.
If anyone else finds an issue with this change, please do comment below.

Many Thanks.

[CaMer0n]

Commit ed36008