New be within matcher and RSpec.deprecate fix

[myronmarston]

This matcher is much nicer than be_close, in my opinion. It should probably only be included in the future 2.1.0 release since it's a new API.

The first commit should probably also be included in the next 2.0.x release, since RSpec.deprecate is already being called here, even though it's defined in rspec-core and we want rspec-expectations to be usable without core.

[dchelimsky]

I merged the deprecate port. Thinking about depending on the deprecated gem in the future, though. WDYT?

[myronmarston]

Add be_within(delta).of(expected) matcher

• Delegate be_close(expected, delta) to be_within
• Deprecate be_close(expected, delta)
• Reads much better.
• The argument ordering is clearer.
• Closed by 7852dbd.

[myronmarston]

Thinking about depending on the deprecated gem in the future, though. WDYT?

I've never used the deprecated gem, but it looks like it does provide nice, flexible deprecation functionality. That said, my feeling is that the current deprecation behavior is pretty sufficient, and I don't anticipate RSpec.deprecate needing much maintenance in the future. It does the simple thing it's intended to do well.

If/when you find that you need more deprecation flexibility than the current RSpec.deprecate, I think it would make sense to move to the deprecated gem rather than make the same updates to the method in core and expectations...but for now I don't think it's worth adding the extra dependency.