Use PHP-based first article day

Instead of adding class to first .article-day
Adding page-cover fade out effect on scroll
Adding article month
Article-year & JavaScript adjustment support

- adding article-year section
- adding javascript adjustment for newly loaded first article day /
month / year
Better file naming
Adjustment for posted-on meta

posted-on meta on stream page will display exact publishing time, since
day time has been displayed by article time divider
Adding hover state color for entry-category
Adding aside template
More obvious sticky post color