Computer environments are now constructed from scratch by a function.  Fixed many, many security holes.

Please do not use getfenv(number).  It caused an incredible amount of global environment leaks.

getfenv is still unsafe.  I enabled the sandbox for it, but ideally, the sandbox should be unneccessary.
Merge branch 'master' into newenv
Merge pull request #4 from ninnghazad/newenv

ftw