Feature migrations up/down (#270)

* Migrations up down

* Add forum model

* Syntactic sugar for db structure changes

* Refactor migrations with $up & $down

* Fix migrations upgrade and downgrade

+ Add option to disable auto migrate

* Add migrate:to command

Usage: php aac migrate:to x (x - database version)

* Show error when mail is not enabled

* Fixes regarding to init.php

* Add migrate command to manually upgrade db, incase auto migrate is disabled

* Fixed rest of the migrations

* Limit max version of database

* Don't allow minus number

* Option to clear specified plugin settings by name

* Version is required

* Fix PHPStan errors

* Unset $up after migration, to prevent executing same migration twice

* Add database version to output

* This is not needed

* Update 5.php

* Set database_auto_migrate on install

* Set blank & color only if current db version supports it

* Fix duplicate function declaration

system/migrations/27-commands.html

@@ -0,0 +1,22 @@
+<table class="myaac-table" style="border-collapse: collapse; width: 100%; height: 72px; border-width: 1px;" border="1"><colgroup><col style="width: 50%;"><col style="width: 50%;"></colgroup>
+	<thead>
+	<tr style="height: 18px;">
+		<td style="height: 18px; border-width: 1px; text-align: center;"><span style="color: #ffffff;"><strong>Words</strong></span></td>
+		<td style="height: 18px; border-width: 1px; text-align: center;"><strong>Description</strong></td>
+	</tr>
+	</thead>
+	<tbody>
+	<tr style="height: 18px;">
+		<td style="height: 18px; border-width: 1px;">!example</td>
+		<td style="height: 18px; border-width: 1px;">This is just an example</td>
+	</tr>
+	<tr style="height: 18px;">
+		<td style="height: 18px; border-width: 1px;">!buyhouse</td>
+		<td style="height: 18px; border-width: 1px;">Buy house you are looking at</td>
+	</tr>
+	<tr style="height: 18px;">
+		<td style="height: 18px; border-width: 1px;"><em>!aol</em></td>
+		<td style="height: 18px; border-width: 1px;">Buy AoL</td>
+	</tr>
+	</tbody>
+</table>