Refactor statistics

I made a new controller to handle statistics. The old statistics have been moved in that controller and a new action has been added to display idle feeds. I also added a menu in the left panel to navigate between the statistics pages.
See #90
Refactor idle feed stats
Fix syntax
Refactor statistics

I made a new controller to handle statistics. The old statistics have been moved in that controller and a new action has been added to display idle feeds. I also added a menu in the left panel to navigate between the statistics pages.
See #90
Refactor idle feed stats
Fix syntax
Refactor and formatting
Merge branch 'stats' of https://github.com/aledeg/FreshRSS into stats

Conflicts:
	app/Controllers/statsController.php
	app/Models/StatsDAO.php
	app/i18n/en.php
	app/i18n/fr.php
	app/layout/aside_stats.phtml
	app/layout/header.phtml
	app/views/index/stats.phtml
	app/views/stats/idle.phtml
	app/views/stats/index.phtml
	app/views/stats/main.phtml
Change behavior when selecting an article

See #524
Before, when the configuration was set so the article is marked as read when selected, if you mark it as unread while it is open and then close it, it is marked again as read. This behavior was not straightforward.
Now, the article is not marked again as read.
Merge pull request #516 from aledeg/stats

Refactor statistics
Add TTL to control feed freshness

https://github.com/marienfressinaud/FreshRSS/issues/250
Minor white space parentheses
Bug global TTL

https://github.com/marienfressinaud/FreshRSS/issues/250
Changelog TTL

https://github.com/marienfressinaud/FreshRSS/issues/250
Merge pull request #525 from aledeg/issue524

Change behavior when selecting an article
Minor #524

https://github.com/marienfressinaud/FreshRSS/issues/524
Prepare statistics for SQLite

Temporarily disable 30-day statistics for SQLite
https://github.com/marienfressinaud/FreshRSS/issues/100
https://github.com/marienfressinaud/FreshRSS/issues/90
SQL: improved performance for adding new articles
SQL: SQLite syntax uniformisation

https://github.com/marienfressinaud/FreshRSS/commit/805c91da98c2f582e279f3c853fba9e43f572419#diff-101042bec0ff3ac9d691b2e77fca3313R7
Flat design based on default template

- stats are not terminated yet
- need reviews

See https://github.com/marienfressinaud/FreshRSS/issues/320