Changes to share the command line

[pkriens]

There are numerous upcoming contestants for 'owning' the command line. Traditionally this is hard coded but this has the disadvantage that it creates a highly coupled network, which is hard to maintain.

This patch uses an annotation and some OSGi/bnd tooling to find all classes that want to add a command to the command line. The AlloyDispatcher gathers all those commands and then parses the command line. A library is used that uses an interface as specification for the options/flags and arguments. The library can then parse the command line, do error reporting, and provide extensive help.

Adding a new main looks like:

 @AlloyMain( name="new" )
 @AlloyMain( name="old" )
 public class OldAndNew {

     @Description("This is an old command")
     interface OldCommand extends Options {
             @Description("This is an old command")
              boolean backup();
     }            

     public void _old(OldCommand options) {
          if ( options.backup() ) 
             ....
     }
 }

Any class in the build will be picked up.

The AlloyDispatcher can set the user A4Preferences, default log level, and class specific loglevels. A few commands like version and prefs are provided to show how the mechanism work.

[pkriens]

@aleksandarmilicevic @eskang @grayswandyr are you ok if these commits that do not affect the language in any way, if I just commit them? We can always revert ... Just want to make a few more infra structure changes so Alloy will be easier to extend in the future.