ci: improve release process, clean up and re-org repo, add automated minification (#143)

* ci: update scripts

* release 2.7.1

* remove tracked stylesheets

* docs: revert stable tag to 2.7.0

* chore: move Plugin source into own dir

* docs: delete info texts

These can now be found in the [project wiki][wiki].

[wiki]: https://github.com/markcheret/footnotes/wiki

* docs: tweak contributing guide

* ci: reflect new directory structure

* chore: update gitignore

* chore: reflect new dir structure

* docs: update documentation

* build(linting): add Husky hooks, Markdown linting, lint all MD files

* fix pre-push command

* fix pre-push command

* build: add stylesheet, JS minification

* ci: add linting steps

* ci: comment out CSS linting step (that's going to be a whole *thing*)

* ci: minify all JS files

* ci: call correct JS file

* chore: lint

* ci: fix PHP linting commands

* chore: increment version constant string

* ci: concat AMP stylesheets

* ci: improve build scripts

* chore: add assets dir

phpdoc.dist.xml

@@ -11,17 +11,13 @@
     <version number="3.0">
         <api format="php">
             <source dsn=".">
-                <path>class</path>
+                <path>src</path>
             </source>
       			<output>docs</output>
-            <ignore hidden="true" symlinks="true">
-            	<path>vendor/*</path>
-            	<path>node-modules/*</path>
-            </ignore>
 						<extensions>
 						  <extension>php</extension>
 						</extensions>
-      			<default-package-name>Footnotes</default-package-name>
+      			<default-package-name>footnotes</default-package-name>
      				<include-source>true</include-source>
         </api>
     </version>