Allow to set the min/max HTML5 attributes for text fields (see #25)

Description
-----------

This is a feature pull request for contao/core-bundle#1622. It changes the current behaviour of `minlength/maxlength` and `minval/maxval` attributes the way that `min/max` HTML5 attributes will be added automatically if the field is a type of `number`.

I am not sure if the implementation is 100% safe and won't cause any side effects, so any feedback is very much welcome!

Commits
-------

e0194fb Allow to set the min/max HTML5 attributes for text form field (contao/core-bundle#1622)
843fc95 Merge branch 'master' into feature/min-max-field-attributes
96a23e0 Fix the coding style

core-bundle/src/Resources/contao/forms/FormTextField.php

@@ -66,10 +66,36 @@ public function __set($strKey, $varValue)
 	{
 		switch ($strKey)
 		{
+			// Treat minlength/minval as min for number type field (#1622)
+			case 'minlength':
+			case 'minval':
+				if ($this->type == 'number')
+				{
+					$this->min = $varValue;
+				}
+				else
+				{
+					$this->arrConfiguration[$strKey] = $varValue;
+				}
+				break;
+
+			// Treat maxlength/maxval as max for number type field (#1622)
 			case 'maxlength':
+			case 'maxval':
 				if ($varValue > 0)
 				{
-					$this->arrAttributes['maxlength'] =  $varValue;
+					if ($this->type == 'number')
+					{
+						$this->max = $varValue;
+					}
+					elseif ($strKey == 'maxlength')
+					{
+						$this->arrAttributes[$strKey] = $varValue;
+					}
+					else
+					{
+						$this->arrConfiguration[$strKey] = $varValue;
+					}
 				}
 				break;
 
@@ -87,6 +113,11 @@ public function __set($strKey, $varValue)
 
 			case 'min':
 			case 'max':
+				$this->arrAttributes[$strKey] = $varValue;
+				$this->arrConfiguration[$strKey . 'val'] = $varValue;
+				unset($this->arrAttributes[$strKey . 'length']);
+				break;
+
 			case 'step':
 			case 'placeholder':
 				$this->arrAttributes[$strKey] = $varValue;
@@ -175,6 +206,27 @@ public function __get($strKey)
 		}
 	}
 
+	/**
+	 * Re-add some attributes if the field type is a number
+	 */
+	public function addAttributes($arrAttributes)
+	{
+		parent::addAttributes($arrAttributes);
+
+		if ($this->type != 'number')
+		{
+			return;
+		}
+
+		foreach (['minlength', 'minval', 'maxlength', 'maxval'] as $name)
+		{
+			if (isset($arrAttributes[$name]))
+			{
+				$this->$name = $arrAttributes[$name];
+			}
+		}
+	}
+
 	/**
 	 * Trim the values
 	 *