_.property support for null and undefined
Implement _.isError
Keys shim misses non enumerable properties
keys shim: use enumBug flag
First and last n via initial/rest
Test for IE11 compat bug
Fixes #1805 -- add an 'official' underscore-semver npm package.
Merge branch 'master' of https://github.com/jashkenas/underscore
#1805 -- remove link to trolly (bur realistic) underscore-semver package
Each test: doesn't loop over new items
Merge pull request #1816 from megawac/changing-col

Each test: doesn't loop over new items
Prevent _.random returning max + 1 in rare cases
Loosen clock skew check on debounce

In fa352605, a sanity check was added to debounce to make sure our clock hadn't skewed earlier. If the debounced function is getting called under load, though, the last called ts can be the same as the current ts when the timeout runs. That causes `last` to be 0, and currently causes the debounced function to fire.
Revert #1739 -- leave _.extend raw, as all iterable properties
Merge pull request #1819 from ewr/master

Loosen clock skew check on debounce
attempting to fix the travis (with guesswork)
Merge pull request #1818 from jawj/master

Prevent _.random returning max + 1 in rare cases
Fixing the Travis\!
Revert "Merge pull request #1818 from jawj/master"

This reverts commit a57169012adee5e4f40d062df57ddcd9e1dcf23e, reversing
changes made to be486a280a8c86eab819505c63216c6c69d8b473.
Merge pull request #1755 from megawac/keys-fix

Keys shim misses non enumerable properties