* Update simplesamlphp-theming.md

* Add theme.controller config setting

class_implements() returns class names without leading backslash

Items in $warnings should either be a string or an array with two values

* Correct xh translations issue #1022

These assets have been moved somewhere else or integrated as part of the new build system, so they are no longer used / necessary.

Before calling npm to install dependencies and build, we need to step into the installation directory. Also, node_modules and the stylesheet.js* byproduct can be removed in production.

This reverts commit 07796176.

The previous "fix" wasn't really fixing anything, it was indeed breaking the code that was changing the submit button, because jquery (and therefore "$") wasn't in scope for the script. Now, once jquery is available for that code, the bug appears again. This is due to an alleged "bug" in chrome, which prevents the button from actually working after it gets disabled. This makes full sense on the other hand, and as soon as we disable it, events won't keep being processed for that button, and as such, the form never gets submitted. This is why we need to submit the form manually.

ClipboardJS is initialised once in the bundle for class="copy",
not initialised on each page that uses it.

This includes the generation of metadata for all hosted entities, even if there's more than one entity defined for a certain type (e.g. multiple SPs or multiple IdPs).

Still missing:

* Metadata converter moved to the admin module.
* Metadata lookup.
* Showing metadata for trusted entities.
* Downloading certificates.
* Move the "clear my discovery choices" link to the new user interface.

Since the class cannot be named "Const" when using namespaces, due to "const" being a reserved word, we needed to rename the class. That requires also some logic in the autoloader to map the old name to the new one.