Better OS X integration

[Don-vip]

Thanks to Stereo I have successfully setup a "Hackintosh" that finally allows me to test JOSM on OS X, in a virtual Machine, by following this guide:

​http://www.macbreaker.com/2014/05/os-x-mavericks-in-virtualbox-with-niresh.html

I find a lot minor issues that I'll try to fix through this ticket:

1. JOSM does not use OS X native LAF by default: fixed in r7480
2. 7u67: Hyperlinks do not work (left click) if Safari is still the default browser
3. 7u67: Right click on hyperlinks do not copy the link to clipboard
4. 7u67: The vertical toolbar is too wide: horizontal space wasted
5. 7u67: The horizontal status bar is too large: vertical space wasted
6. 7u67: The icons in preferences dialog are ridiculously small
7. 7u67: Java dock icon is displayed instead of JOSM one if launched with Java Web Start
8. 7u67: Toggle dialogs do not collapse when we left-click on their title bar

Many other points to come I think.