Merge pull request #3 from fsoikin/master

In Vm.CheckVmWithoutError, wrap exceptions in ShovelException before rethrowing them.
Removed GenRun completely.
Merge branch 'master' of github.com:mbrezu/Shovel
BREAKING CHANGE: External code is less exposed to Shovel.Value's ugly guts (StructLayout etc.).
Removed the 'safe' flag from RunVm & co.
Open certain aspects of VM state (frames, environments, stack, etc.) to enable inspection of a running program.