2.6.0

Upgraded to use Chai's new lazy-messages feature (as of Chai 1.9.2), which speeds up all asserters (since calculating the message can take some time) and avoids triggering any getters (e.g. those installed to create deprecation warnings). For examples of each of these problems, both of which are now fixed, see respectively #30 and #38.

This means the minimum version of Chai now required alongside Sinon–Chai is 1.9.2; the peer dependency requirement has been updated accordingly.