feat: update analytics so to meet IABv2 requirements

- https://iabtechlab.com/wp-content/uploads/2017/12/Podcast_Measurement_v2-Dec-20-2017.pdf
  - no IP address is ever stored on the server. Only aggregate data is stored in the dababase.
  - rolling 24-hour window
  - castopod does not do pre-load
  - IP Blacklisting https://github.com/client9/ipcat
  - user-agent Filtering https://github.com/opawg/user-agents
  - ignores 2 bytes range "Range: 0-1" (performed by official Apple iOS Podcast app)
  - in case of partial content, adds up all requests to check >1mn was downloaded
  - identifying Uniques is done with a combination of IP Address and User Agent
- add AMcharts
- add some graphs
- add regions to analytics
- add ipcat blacklist
- enhance useragents performances
- add filesize and header size in order to calculate 1mn downloads
- update publisher ID3 field
- update castopod icon
- add disclaimer and warning import form translation
- update docs/setup-development.md

closes #10

app/Models/AnalyticsPodcastsByEpisodeModel.php

@@ -0,0 +1,113 @@
+<?php
+
+/**
+ * Class AnalyticsPodcastsByEpisodeModel
+ * Model for analytics_podcasts_by_episodes table in database
+ * @copyright  2020 Podlibre
+ * @license    https://www.gnu.org/licenses/agpl-3.0.en.html AGPL3
+ * @link       https://castopod.org/
+ */
+
+namespace App\Models;
+
+use CodeIgniter\Model;
+
+class AnalyticsPodcastsByEpisodeModel extends Model
+{
+    protected $table = 'analytics_podcasts_by_episode';
+
+    protected $allowedFields = [];
+
+    protected $returnType = \App\Entities\AnalyticsPodcastsByEpisode::class;
+    protected $useSoftDeletes = false;
+
+    protected $useTimestamps = false;
+
+    /**
+     * @param int $podcastId, $episodeId
+     *
+     * @return array
+     */
+    public function getDataByDay(int $podcastId, int $episodeId = null): array
+    {
+        if (!$episodeId) {
+            if (
+                !($found = cache(
+                    "{$podcastId}_analytics_podcast_by_episode_by_day"
+                ))
+            ) {
+                $lastEpisodes = (new EpisodeModel())
+                    ->select('id, season_number, number, title')
+                    ->orderBy('id', 'DESC')
+                    ->where(['podcast_id' => $podcastId])
+                    ->findAll(5);
+
+                $found = $this->select('age AS X');
+
+                $letter = 97;
+                foreach ($lastEpisodes as $episode) {
+                    $found = $found
+                        ->selectSum(
+                            '(CASE WHEN `episode_id`=' .
+                                $episode->id .
+                                ' THEN `hits` END)',
+                            chr($letter) . 'Y'
+                        )
+                        ->select(
+                            '"' .
+                                (empty($episode->season_number)
+                                    ? ''
+                                    : $episode->season_number) .
+                                (empty($episode->number)
+                                    ? ''
+                                    : '-' . $episode->number . '/ ') .
+                                $episode->title .
+                                '" AS ' .
+                                chr($letter) .
+                                'Value'
+                        );
+                    $letter++;
+                }
+
+                $found = $found
+                    ->where([
+                        'podcast_id' => $podcastId,
+                        'age <' => 60,
+                    ])
+                    ->groupBy('X')
+                    ->orderBy('X', 'ASC')
+                    ->findAll();
+
+                cache()->save(
+                    "{$podcastId}_analytics_podcast_by_episode_by_day",
+                    $found,
+                    14400
+                );
+            }
+            return $found;
+        } else {
+            if (
+                !($found = cache(
+                    "{$podcastId}_{$episodeId}_analytics_podcast_by_episode_by_day"
+                ))
+            ) {
+                $found = $this->select('date as labels')
+                    ->selectSum('hits', 'values')
+                    ->where([
+                        'episode_id' => $episodeId,
+                        'podcast_id' => $podcastId,
+                    ])
+                    ->groupBy('labels')
+                    ->orderBy('labels', 'ASC')
+                    ->findAll();
+
+                cache()->save(
+                    "{$podcastId}_{$episodeId}_analytics_podcast_by_episode_by_day",
+                    $found,
+                    14400
+                );
+            }
+            return $found;
+        }
+    }
+}