Add 1.4.3 release post by @BenBalter for master branch.
Update History.markdown with 1.4.3 release.
Require Liquid 2.5.5 <= x < 2.6
update dat gemspec
Make doc menus more reusable
Merge pull request #1947 from jekyll/1-4-3-release-info
Update history to reflect merge of #1947
Lock Maruku to 0.7.0

This fixes the errors we see in our tests due to the upgrade to Maruku
0.7.1
Merge pull request #1958 from jekyll/lock-down-maruku
Update history to reflect merge of #1958
Merge pull request #1953 from troyswanson/dataify-docs
Update history to reflect merge of #1953 [ci skip]