Refactor unsafe

[jtenner]

@dcodeIO seemed to think that we could redesign how reallocateUnsafe() works for ArrayBuffer. This pull request aims to do the following things:

• Standardize reallocateUnsafe and allocateUnsafe to avoid zeroing of data
• Add reallocateZeroedUnsafe and allocateZeroedUnsafe to zero out the data
• Replace instances of unsafe methods to reallocateZeroedUnsafe and allocateZeroedUnsafe respectively for backwards compatibility

[jtenner]

It's become painfully obvious that this pull request is not going to solve the problem (if it even was a problem in the first place.)

Closing in favor of #535 obviously.