Make it easier to develop plug-ins and extensions as a single package

[Nicklas Nordborg]

This is not so streamlined at the moment. Since extensions are requrired to be located in the WEB-INF/extensions folder, the plug-in auto-installation wizard will normally not find plug-ins that are part of the extension. Currently there are three workarounds:

• Manually install each plug-in. It is not hard but takes a rather long time if there are more than one plug-in.
• Configure the server to use the WEB-INF/extensions folder as the plug-ins directory. While this should work, it may be difficult in practice if there are already plug-in installed in a another location.
• The extension/plug-in are released as separate components (JAR-files). One JAR file goes into the extensions directory and one into the plug-ins directory. The drawback with this solution is that the JAR files are handled by different class loaders and it is more or less impossible for the extension to use functionality in the plug-in and vice versa. And since the JAR files are located in separate directory structures it is hard to specify a Classpath in the manifest file inside the JARs.

A simple solution to all of the problems would be to add an option in the plug-in auto-installation wizard to also scan the extensions folder.

[Nicklas Nordborg]

(In [4859]) Fixes #1273: Make it easier to develop plug-ins and extensions as a single package