disabled opAssign prevents some valid usage about tempalloc

[dsimcha]

I'll think about enabling it. I don't even remember exactly why I disabled it. I think it was just that I didn't see a use case at the time and didn't feel like making some decision on its semantics (i don't remember the details), so I just decided to disable it as the path of least resistance. You're right, though, that allowing manually created stacks makes allowing assignment look a lot more useful.

[dsimcha]

Now that I look at the code a little more, there are a whole bunch of details about lifetime management/postblits/destructors that no longer make sense given the manual stack creation modification. I'll clean them up and document them better, but that's going to take a day or two.

[dsimcha]

Fixed. I also cleaned up some resource management, documentation, error handling and performance issues.

[DmitryOlshansky]

Thanks, I'll try new version then.