resolves #1138 fix spacing around checkbox in checklist
resolves #1144 fix includes that reference absolute Windows paths

- fix support for absolute Windows path as target of include directive
- add test for include directive with absolute path target
- add tests for UriSniffRx
Load Slim's include plugin

https://github.com/slim-template/slim/blob/master/doc/include.md
Merge pull request #1151 from jirutka/slim-include

Load Slim’s include plugin
Merge pull request #1139 from mojavelinux/issue-1138

resolves #1138 fix spacing around checkbox in checklist
Merge pull request #1145 from mojavelinux/issue-1144

resolves #1144 fix includes that reference absolute Windows paths
only load slim/include if Slim >= 2.1
resolves #1127 add key documentation links to README

- also adds them to asciidoctor.org home page
Merge pull request #1153 from mojavelinux/issue-1127

resolves #1127 add key documentation links to README
resolves #1090 assign title to preface node

- assign title to preface node based on value of preface-title attribute
remove some dead code
resolves #1085 add append method as alias to << on AbstractBlock
Merge pull request #1156 from mojavelinux/issue-1085

resolves #1085 add append method as alias to << on AbstractBlock
Add Inch CI badge
Merge pull request #1157 from jirutka/inch-badge

Add Inch CI badge
Remove webkitAllowFullScreen and mozallowfullscreen from block_video

These attributes are already deprecated and not needed since Firefox 18
and Chrome/Chromium 27.
Merge pull request #1160 from jirutka/patch-1

Remove webkitAllowFullScreen and mozallowfullscreen from block_video
Add Code Climate badge
Merge pull request #1164 from jirutka/climate-badge

Add Code Climate badge
put error class after error message in cli output