Automatic inclusion of ImageJ PluginFilter

[sjcross]

Automatically scan ImageJ for PluginFilter classes, which could be included as modules. This would, by default, add lots more functionality without the need to explicitly create modules. Will require each plugin to be scanned for parameters.

Could also be possible with other types of Plugin. Also need to consider the scijava plugin format.

[sjcross]

PluginFilter classes may be difficult, as parameters are announced until the dialog is run. A better option would be to automatically wrap ImageJ Ops (#174)