Fix bug with invalid example IDs

This reverts a hotfix #809
that removed the changes in favour of a proper fix for
#620

Generating example IDs from example titles can be brittle if there
are unexpected characters in titles. Use the IDs and
fall back to default ones and uses the solution from #620 to fix
duplicate IDs

lib/metalsmith.js

@@ -217,8 +217,7 @@ module.exports = metalsmith(__dirname) // __dirname defined by node.js: name of
         getMacroOptions: getMacroOptions
       },
       filters: {
-        highlight: highlighter,
-        kebabCase: string => string.replace(/\s+/g, '-').toLowerCase()
+        highlight: highlighter
       },
 
       // Markdown engine options

views/partials/_example.njk

@@ -13,7 +13,12 @@
 {% endif %}
 {% set exampleTitle = exampleTitle + " example" %}
 
-{% set exampleId = exampleTitle | kebabCase %}
+{% set exampleId = params.id | default("example-" + params.example) %}
+
+{% if params.titleSuffix %}
+  {% set exampleId = exampleId + '-' + params.titleSuffix %}
+{% endif %}
+
 {% if params.open %}
   {% set exampleId = exampleId + '-open' %}
 {% endif %}