Add some performance and stability enhancements

Bugs fixed:
Crashing when trying to display a complex grid
http://www.sencha.com/forum/showthread.php?158687

Crash when changing tpl property in a templatecolumn
http://www.sencha.com/forum/showthread.php?156672

Codegeneration now properly uses layout config
http://www.sencha.com/forum/showthread.php?193135
http://www.sencha.com/forum/showthread.php?178369

Maintenance:
New 3.x Projects now default to using cachefly urls for 3.4 in project settings

No longer allow users to open projects created with Sencha Architect