Minor fixes + sitemap generation

[tlienart]

• Also skip code eval on delay #621 skip code eval for delayed pages
• Anchor generation should remove quotes #599 remove quotes for anchor generation
• Generate sitemap automatically #491 add sitemap generation
• introduce aliases for common global variables
  • prefix => prepath
  • base_path => prepath
  • base_url => website_url

Sitemap generation

global vars

• website_url (also used for RSS)
• generate_sitemap true|false

local vars

• sitemap_exclude false|true
• sitemap_changefreq "monthly" | "always", "hourly", "daily", "weekly", "yearly", "never"
• sitemap_lastmod (extracted from file last modification)
• sitemap_priority 0.5 | [0, 1]

hfun

For a HTML page (e.g. landing page or other custom html page)

{{sitemap_opts exclude}} 

or

{{sitemap_opts yearly 0.7}}

[schneiderfelipe]

Awesome! Thanks for this one!