Replace existing autoloader with Composer-supplied

- Move Friendica namespace to `src`
- Move required `ezyang/htmlpurifier` to vendor
- Remove existing static autoloader
- Change boot.php reference to the autoloader

vendor/ezyang/htmlpurifier/library/HTMLPurifier/AttrDef/CSS/BackgroundPosition.php

@@ -0,0 +1,157 @@
+<?php
+
+/* W3C says:
+    [ // adjective and number must be in correct order, even if
+      // you could switch them without introducing ambiguity.
+      // some browsers support that syntax
+        [
+            <percentage> | <length> | left | center | right
+        ]
+        [
+            <percentage> | <length> | top | center | bottom
+        ]?
+    ] |
+    [ // this signifies that the vertical and horizontal adjectives
+      // can be arbitrarily ordered, however, there can only be two,
+      // one of each, or none at all
+        [
+            left | center | right
+        ] ||
+        [
+            top | center | bottom
+        ]
+    ]
+    top, left = 0%
+    center, (none) = 50%
+    bottom, right = 100%
+*/
+
+/* QuirksMode says:
+    keyword + length/percentage must be ordered correctly, as per W3C
+
+    Internet Explorer and Opera, however, support arbitrary ordering. We
+    should fix it up.
+
+    Minor issue though, not strictly necessary.
+*/
+
+// control freaks may appreciate the ability to convert these to
+// percentages or something, but it's not necessary
+
+/**
+ * Validates the value of background-position.
+ */
+class HTMLPurifier_AttrDef_CSS_BackgroundPosition extends HTMLPurifier_AttrDef
+{
+
+    /**
+     * @type HTMLPurifier_AttrDef_CSS_Length
+     */
+    protected $length;
+
+    /**
+     * @type HTMLPurifier_AttrDef_CSS_Percentage
+     */
+    protected $percentage;
+
+    public function __construct()
+    {
+        $this->length = new HTMLPurifier_AttrDef_CSS_Length();
+        $this->percentage = new HTMLPurifier_AttrDef_CSS_Percentage();
+    }
+
+    /**
+     * @param string $string
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return bool|string
+     */
+    public function validate($string, $config, $context)
+    {
+        $string = $this->parseCDATA($string);
+        $bits = explode(' ', $string);
+
+        $keywords = array();
+        $keywords['h'] = false; // left, right
+        $keywords['v'] = false; // top, bottom
+        $keywords['ch'] = false; // center (first word)
+        $keywords['cv'] = false; // center (second word)
+        $measures = array();
+
+        $i = 0;
+
+        $lookup = array(
+            'top' => 'v',
+            'bottom' => 'v',
+            'left' => 'h',
+            'right' => 'h',
+            'center' => 'c'
+        );
+
+        foreach ($bits as $bit) {
+            if ($bit === '') {
+                continue;
+            }
+
+            // test for keyword
+            $lbit = ctype_lower($bit) ? $bit : strtolower($bit);
+            if (isset($lookup[$lbit])) {
+                $status = $lookup[$lbit];
+                if ($status == 'c') {
+                    if ($i == 0) {
+                        $status = 'ch';
+                    } else {
+                        $status = 'cv';
+                    }
+                }
+                $keywords[$status] = $lbit;
+                $i++;
+            }
+
+            // test for length
+            $r = $this->length->validate($bit, $config, $context);
+            if ($r !== false) {
+                $measures[] = $r;
+                $i++;
+            }
+
+            // test for percentage
+            $r = $this->percentage->validate($bit, $config, $context);
+            if ($r !== false) {
+                $measures[] = $r;
+                $i++;
+            }
+        }
+
+        if (!$i) {
+            return false;
+        } // no valid values were caught
+
+        $ret = array();
+
+        // first keyword
+        if ($keywords['h']) {
+            $ret[] = $keywords['h'];
+        } elseif ($keywords['ch']) {
+            $ret[] = $keywords['ch'];
+            $keywords['cv'] = false; // prevent re-use: center = center center
+        } elseif (count($measures)) {
+            $ret[] = array_shift($measures);
+        }
+
+        if ($keywords['v']) {
+            $ret[] = $keywords['v'];
+        } elseif ($keywords['cv']) {
+            $ret[] = $keywords['cv'];
+        } elseif (count($measures)) {
+            $ret[] = array_shift($measures);
+        }
+
+        if (empty($ret)) {
+            return false;
+        }
+        return implode(' ', $ret);
+    }
+}
+
+// vim: et sw=4 sts=4