feat(template): move all custom variables to default `_config.yml`

BREAKING CHANGE: Now all custom variables go to `_config.yml`, original `var.yml` will no longer available. all related template tags have been update for new variable structure.
Merge branch 'master' of github.com:sparanoid/sparanoid.com

* 'master' of github.com:sparanoid/sparanoid.com:
  chore: update external link
  chore: update link
chore: remove additional `dist` cleanup, read more: http://jekyllrb.com/docs/usage/
feat(style): make highlighter theme works for all color scheme (hint: LESS color functions)
feat: split configuration files into 3 files for better user experience
fix(template): update footer credit
chore: fix typo
chore: update init config
chore(style): tweak syntax highlighter background
Bump version to 24.0.9
feat(style): update `.browser` style