This commit allows a plugin.xml to use a reference to data defined in the pom.xml. This reduces duplicate data.

For instance, in plugin.xml, one could now define the version number by referring to the version number of the
maven artifact:

  <version>${project.version}</version>

Note that plugin.xml files that are processed using the old Apache Ant based build, will not be processed correctly.

This commit copies version number, author and description from plugin.xml to pom.xml. This makes the same information available as Maven metadata.

When Ant support is dropped, the duplicate data in the plugin.xml should be replaced by a filter (which takes the data from the pom.xml).

I continue to be thoroughly confused by having two directories per plugin, one for the plugin sources, and one for the maven build. This commit merges both directories.

As a side effect, various plugin unit tests are now executed by default. Some failed, for which I applied fixes.

This commit also adds some plugins to the Maven structure that previously were not.

* remove unused global.css

* OF-1334 Don't do CSRF check unless actions are requested

OF-1332 Update MySQL JDBC client to latest version.

OF-1310 Fix removal of last item of pubsub node

OF-1326: Improve sharing of the BOSH context

OF-1277 -- Change setting name to Invisible Login and Status

The Openfire plugin developer guide states that 'additinal' files should be in /classes/. Apparently, the old Ant script also included any files in the /src/. The new Maven structure does not.
To work around compatibility issues, code that was in /src/ is now moved to /classes/. This should work with both Ant, as well as Maven.

Additionally, this plugin now makes use of the new HttpBindManager API for registering contexts with the BOSH context. I do wonder if this plugin has any reason to be here though. Can't it just run its own embedded Jetty server?

Intead of using a parent context, a collection of Jetty handlers can be used to dynamically add/remove functionality to the BOSH context.

This commit replaces the parent context instance with a ordered list of handlers, which will attempt to process a request by:

1. Checking if this is a BOSH request
2. Checking if this is a request for BOSH metadata
3. Check if an extension was provided that can handle the request
4. Try to serve static content as a last resort.

In step 3, a collection of handlers is used, that can be modified at runtime. This allows plugins to register/remove handlers.

The entire collection of handlers (1 to 4) is maintained with a lifecycle that's different from the embedded Jetty server that uses them. This
allows the collection to survive a server reconfiguration, as well as act independent of the 'enabled' state of the BOSH service.

* OF-1325 -- Implement separate History settings in Client Control

* OF-1325 -- Implement separate History settings in Client Control

* OF-1325 -- Implement separate History settings in Client Control

Openfire repeatedly searches for the same UserDN values. This cache should alleviate the backend storage and improve performance.

OF-1324 limit outbound s2s queue

Non-functional changes

These add nothing, but warnings in tooling.

These statements do nothing but generate warnings. Easily fixed.

Javadoc comment are dangling if they don't belong to any class, method or field. For example a Javadoc comment in between method declarations that have their own javadoc comments.

These generate needless warnings, which are in most instances easily solved. By far most problems occur in the license block that's in most files.

This commit adds an upper-limit to the amount of stanzas that can be queued in an outgoing
session promise. Any data that won't fit in the queue is rejected immediately. Note that
this can lead to a situation where later stanzas are rejected before stanzas that or sent
earlier (but got in the queue).

OF-1311: Don't assume values are Strings.

OF-1321: Proper null-check to avoid stacktrace with stale session.

By default, the Maven structure uses the Maven artifactId value as the name for a plugin.
Maven artifactIds typically include tokens that will cause problems, such as dashes and dots.
The plugin name is used in various places, that all have limitations: filenames (the jar file
itself, the i18n files), package names (for the java files generated from JSPs), etc.

This commit allows the name of the plugin to be overridden using a maven property 'plugin.name'
and includes instructions on what the best format is.

For plugins to be able to use the tags used in the admin console, the tags should be distributed in a library. By making this library a Maven module, plugins can define the library as a dependency.

Note that the admin.tld file is duplicated, but *slightly* modified in the Maven module: the path of the tags is different (META-INF vs WEB-INF).