Escape unicode characters
Fixes #2905
Correction of grammatical error and also consistent formatting/correct filename of `_config.yml`
remove watch since it default in 2.4.0
Add test for Use per-post permalinks ending in .htm
Allow per post permalinks to end in `.htm`
Fixes #2920
Merge pull request #2911 from charlesbaynham/minor-grammatical-error
Update history to reflect merge of #2911 [ci skip]
Merge pull request #2922 from igas/patch-1
Update history to reflect merge of #2922 [ci skip]
Include my mathml.rb plugin under Tags.

mathml.rb is a plugin to convert TeX mathematics into MathML.
Merge pull request #2937 from tmthrgd/patch-1
Update history to reflect merge of #2937 [ci skip]
Add note about using the github-pages gem properly
Move it down a little
jekyll build/serve --force_polling option to docs
Merge pull request #2943 from rusikf/patch-7
Update history to reflect merge of #2943 [ci skip]
Merge pull request #2906 from pathawks/escape-css-characters
Update history to reflect merge of #2906 [ci skip]
Fix code example for media query mixin

It was using an old variable name (`$palm`) instead of the current one (`$on-paln`).