* inform user about Twig cache failure on installation, instead of http 500 error

* when dir system/cache is not writable by the webserver, then show some
nice notice to the user about it instead of http 500 error
* remember client version and usage stats checkbox in session on install
* fixed some small warning introducted yesterday about
highscores_ids_hidden
* updated TODO

system/init.php

@@ -149,7 +149,7 @@ $config['data_path'] = $tmp;
 unset($tmp);
 
 // new config values for compability
-if($config['highscores_ids_hidden'] == null) {
+if(!isset($config['highscores_ids_hidden'])) {
 	$config['highscores_ids_hidden'] = array();
 }
 

system/migrations/19.php

@@ -1,3 +1,3 @@
 <?php
-// this migrations has been removed, but file kept for compability
+// this migration has been removed, but file kept for compability
 ?>

system/templates/install.config.html.twig

@@ -23,7 +23,7 @@
 				<br/>
 				<select name="vars[client]" id="vars_client">
 					{% for id, version in clients %}
-					<option value="{{ id }}">{{ version }}</option>
+					<option value="{{ id }}"{% if session['var_client'] is not null and session['var_client'] == id %} selected{% endif %}>{{ version }}</option>
 					{% endfor %}
 				</select>
 			</td>
@@ -38,7 +38,7 @@
 				</label>
 				<br/>
 				<input type="hidden" value="0" name="vars[usage]">
-				<input type="checkbox" name="vars[usage]" id="vars_usage" value="1" checked/>
+				<input type="checkbox" name="vars[usage]" id="vars_usage" value="1"{% if session['var_usage'] is null or session['var_usage'] == 1 %} checked{% endif %}/>
 			</td>
 			<td>
 				<em>{{ locale.step_config_usage_desc }}</em>