NeTV release 20 notes

Release 20 notes
Minor release. Following fixes/upgrades are made available:

Control Panel

 * Control panel now locks out keys during transition animations (to prevent double-press of keys causing overshoot of say, scrolling or tab selection)
 * Various minor bug fixes

System

 * Reliably avoid running 2 instances of NeTVBrowser at the same time
 * New behavior for multitab/tab commands. It is now possible to show/hide tabs without destroying them.
 * Keep-alive timer was disabled by accident. Use KEEPALIVE command to disable it.
 * New HTTP API commands & demo page available (see http://wiki.chumby.com/index.php/NeTV_web_services)