Lightweight command syntax

[tucnak]

We need a super lightweight syntax of creating simple flag-less commands. Something like this would be great:

app := climax.New("appname")

app.Comm("command", "i am command", func (ctx climax.Context) {
    return 0;
});

[ccpaging]

Try:

type Application struct {
	Version string // `1.5`
	Command

	Commands []*Command
	Topics   []*Topic
	Groups   []*Group

	// Default is a default handler. It gets executed if there are
	// no command line arguments (except the program name), when
	// otherwise, by default, the help entry is being shown.
	Default CmdHandler

	ungroupedCmdsCount int
}