Update of the Native Client MAME Port

I finally got around to update the  Native Client MAME port in the Chrome Webstore.
The update features two new ROMs (Looping and Super Tank) which were generously
made available by Reinhard Stompe.
All ROMs can be conveniently selected from that start page.

If you are using Chome -- and you should -- you can install MAME from this link:

MAME in the Chrome Webstore

Details:

• The port  is based on MAME version 0.147u2. 
• In order to keep its size reasonable and because of performance concerns many of the more recent CPUs together with the ROMs using them are not supported.
• This still leaves the number of supported ROMs at over 17000.
• Thanks to cleanup in the upstream code base the port was vastly simpler than the original one described  here. 
• Patches will be posted here shortly.