re: Tools: Spelling fixes

[Dan Kegel]

Austin wrote:
> only used for optimization, so just check for a very small set of
> - criteria that guarantee the types are equivalent; assume every thing
> - criteria that guarantees the types are equivalent; assume everything

The original was correct, please don't change that.
Firstly, it's not a spelling problem;
secondly, in England, it's correct to consider a set of something plural.

The rest of the changes in this patch seem ok.
- Dan