Remove PHP 5.3 support from composer configuration

PSR-2 fix for ADFS module

This reverts commit b9f92f33.

Provide OID mapping for sshPublicKey

I have been maintaining the PHP LDAP EXOP patch for a few years,
which include the ldapwhoami() function. This has finally made its
way into PHP distribution and will be available in PHP 7.3, but
with a modified prototype.

This changes adapts to this API change. While there, also update
exception handling on par with recent SimpleSAMLphp code.

See issue #593 for a problem description.
SimpleSamlPHP makes use of unsafe inline Javascript and CSS elements.
Although most generated HTML uses SimpleSamlPHP's own headers, the
keepPost option in an authentication request uses the headers of
the PHP application it is sent from. This forces web applications
using SimpleSamlPHP to allow 'unsafe-inline' in their Content
Security Policy.

This commit fixes this issue for the keepPost page ''only'', to
allow PHP applications using SimpleSamlPHP to use a more strict
Content Security Policy. This does not take away from possible
XSS vulnerabilities in other parts of SimpleSamlPHP.

ADFS-module: Set enctype on post-form

Without proper enctype, every space in $wresult will be converted to a +

bugfix: Make the core:TargetedID authproc filter return also a NameID object instead of its string representation.

bugfix: NameIDs are created now as objects, so their information can't any longer be accessed as an array.

Fix XML validation failure with leading/trailing whitespace

Add missing 'required' value

Fixes:

Aug  8 20:44:18 simplesamlphp-2 IDP-MOO[3845]: 3 [d01bee1f99] SimpleSAML_Error_Exception: Error 8 - Undefined index: required
Aug  8 20:44:18 simplesamlphp-2 IDP-MOO[3845]: 3 [d01bee1f99] Backtrace:
Aug  8 20:44:18 simplesamlphp-2 IDP-MOO[3845]: 3 [d01bee1f99] 4 /apps/simplesamlphp/simplesamlphp/www/_include.php:86 (SimpleSAML_error_handler)
Aug  8 20:44:18 simplesamlphp-2 IDP-MOO[3845]: 3 [d01bee1f99] 3 /apps/simplesamlphp/simplesamlphp/modules/core/templates/frontpage_config.tpl.php:91 (require)
Aug  8 20:44:18 simplesamlphp-2 IDP-MOO[3845]: 3 [d01bee1f99] 2 /apps/simplesamlphp/simplesamlphp/lib/SimpleSAML/XHTML/Template.php:405 (SimpleSAML_XHTML_Template::show)
Aug  8 20:44:18 simplesamlphp-2 IDP-MOO[3845]: 3 [d01bee1f99] 1 /apps/simplesamlphp/simplesamlphp/modules/core/www/frontpage_config.php:198 (require)
Aug  8 20:44:18 simplesamlphp-2 IDP-MOO[3845]: 3 [d01bee1f99] 0 /apps/simplesamlphp/simplesamlphp/www/module.php:135 (N/A)

Class name typo causes fatals on some pages

This would mean that any code using this helper function could not
use the ldap.filter option. It's a followup to commit
ff5497e9 which fixed this for the
`login()` method but not for the `searchfordn()` method.