Feature/new archiving (#2335)

* Change archiving config page layout

I've changed some wording and moved actions into a
maintenance section.

* Update purge action

Now we have more control on the purge action. The configuration allows
us to choose what to keep and what to discard in a more precise way.
At the moment, the configuration applies for all feeds.

* Add purge configuration on feed level

Now the extend purge configuration is available on feed level.
It is stored as attributes and will be used in the purge action.

* Update purge action

Now the purge action uses the feed configuration if it exists and
defaults on user configuration if not.

* Add empty option in period list

* Fix configuration warnings

* Add archiving configuration on categories

See #2369

* Add user info back

* Add explanations in UI

* Fixes for SQLite + error + misc.

* Fix invalid feed reference

* Short array syntax

Only for new code, so far

* Fix prefix error

* Query performance, default values

Work in progress

* Fix default values and confirm before leaving

Form cancel and confirm changes before leaving were broken.
And start taking advantage of the short echo syntax `<?= ?>` as we have
moved to PHP 5.4+

* More work

* Tuning SQL

* Fix MariaDB + performance issue

* SQL performance

* Fix SQLite bug

* Fix some attributes JSON encoding bugs

Especially for SQLite export/import

* More uniform, fix bugs

More uniform between global, category, feed settings

* Drop special cases for old articles during refresh

Instead will use lastSeen date with the new archiving logic.
This was generating problems anyway
https://github.com/FreshRSS/FreshRSS/issues/2154

* Draft drop index keep_history

Not needed anymore

* MySQL typo

Now properly tested with MySQL, PostgreSQL, SQLite

* More work for legacy values

Important to avoid overriding user's preference and risking deleting
data erroneously

* Fix PHP 7.3 / 7.4 warnings

@aledeg "Trying to use values of type null, bool, int, float or resource
as an array (such as $null["key"]) will now generate a notice. "
https://php.net/migration74.incompatible

* Reintroduce min articles and take care of legacy parameters

* A few changes forgotten

* Draft of migration + DROP of feed.keep_history

* Fix several errors

And give up using const for SQL to allow multiple database types (and we
cannot redefine a const)

* Add keep_min to categories + factorise archiving logic

* Legacy fix

* Fix bug yield from

* Minor: Use JSON_UNESCAPED_SLASHE for attributes

And make more uniform

* Fix sign and missing variable

* Fine tune the logic

3 files changed, 19 insertions, 2 deletions

diff --git a/app/i18n/oc/conf.php b/app/i18n/oc/conf.php
index 76c41911e..e8de3b089 100644
--- a/app/i18n/oc/conf.php
+++ b/app/i18n/oc/conf.php
@@ -5,11 +5,20 @@ return array(
 		'_' => 'Archius',
 		'advanced' => 'Avançat',
 		'delete_after' => 'Levar los articles aprèp',
+		'exception' => 'Purge exception',	//TODO - Translation
 		'help' => 'Mai d’opcions son disponiblas dins la configuracion individuala dels fluxes',
-		'keep_history_by_feed' => 'Nombre minimum d’articles de servar per flux',
+		'keep_favourites' => 'Never delete favourites',	//TODO - Translation
+		'keep_min_by_feed' => 'Nombre minimum d’articles de servar per flux',
+		'keep_labels' => 'Never delete labels',	//TODO - Translation
+		'keep_unreads' => 'Never delete unreads',	//TODO - Translation
+		'maintenance' => 'Maintenance',	//TODO - Translation
 		'optimize' => 'Optimizar la basa de donada',
 		'optimize_help' => 'De far de temps en temps per redusir la talha de la basa de donadas',
+		'policy' => 'Purge policy',	//TODO - Translation
+		'policy_warning' => 'If no purge policy is selected, every article will be kept.',	//TODO - Translation
 		'purge_now' => 'Purgar ara',
+		'keep_max' => 'Maximum number of articles to keep',	//TODO - Translation
+		'keep_period' => 'Maximum age of articles to keep',	//TODO - Translation
 		'title' => 'Archius',
 		'ttl' => 'Actualizar pas automaticament mai sovent que',
 	),
diff --git a/app/i18n/oc/gen.php b/app/i18n/oc/gen.php
index 7ab56368f..928377997 100644
--- a/app/i18n/oc/gen.php
+++ b/app/i18n/oc/gen.php
@@ -162,6 +162,13 @@ return array(
 		'nothing_to_load' => 'I a pas mai d’articles',
 		'previous' => 'Precedent',
 	),
+	'period' => array(
+		'days' => 'days',	//TODO - Translation
+		'hours' => 'hours',	//TODO - Translation
+		'months' => 'months',	//TODO - Translation
+		'weeks' => 'weeks',	//TODO - Translation
+		'years' => 'years',	//TODO - Translation
+	),
 	'share' => array(
 		'blogotext' => 'Blogotext',
 		'diaspora' => 'Diaspora*',
diff --git a/app/i18n/oc/sub.php b/app/i18n/oc/sub.php
index eae9dff29..0f465d7ca 100644
--- a/app/i18n/oc/sub.php
+++ b/app/i18n/oc/sub.php
@@ -12,6 +12,7 @@ return array(
 	'category' => array(
 		'_' => 'Categoria',
 		'add' => 'Ajustar una categoria',
+		'archiving' => 'Archivar',
 		'empty' => 'Categoria voida',
 		'information' => 'Informacions',
 		'new' => 'Nòva categoria',
@@ -39,7 +40,7 @@ return array(
 			'help' => 'Escrivètz una recèrca per linha.',
 		),
 		'information' => 'Informacions',
-		'keep_history' => 'Nombre minimum d’articles de servar',
+		'keep_min' => 'Nombre minimum d’articles de servar',
 		'moved_category_deleted' => 'Quand escafatz una categoria, sos fluxes son automaticament classats dins <em>%s</em>.',
 		'mute' => 'mut',
 		'no_selected' => 'Cap de flux pas seleccionat.',