Fix #2037. Major overhaul of settings page.
Fix #2037. Major overhaul of settings page.

Convert all tables to 'data::' directives.

Replace inline literals with code blocks for better readability.

Per suggestion from Avaris on IRC:
- Section rename: "Path metadata" to "Metadata" and move over AUTHOR and
  all *_METADATA options.
- Merge "Date format and locale" and "Timezone" into a new section "Time
  and Date" and move over TIMEZONE, DEFAULT_DATE, DATE_FORMATS,
  DEFAULT_DATE_FORMAT.
- Move RELATIVE_URL under 'URL settings'. Here, convert URL settings
  example from a 4-bullet inline literal to a single code block for
  better readability in both source and output.
- Move *_TEMPLATE options under "Templates".

Cosmetic and wording updates to accommodate the above changes and
provide a consistent layout.

Scheirle/pelican,douglaskastle/pelican,lucasplus/pelican,avaris/pelican,iKevinY/pelican,farseerfc/pelican,talha131/pelican,zackw/pelican,getpelican/pelican,Rogdham/pelican,ingwinlu/pelican,douglaskastle/pelican,Rogdham/pelican,farseerfc/pelican,douglaskastle/pelican,lucasplus/pelican,Scheirle/pelican,lucasplus/pelican,talha131/pelican,iKevinY/pelican,getpelican/pelican,zackw/pelican,avaris/pelican,ingwinlu/pelican,Rogdham/pelican,Scheirle/pelican,zackw/pelican