Add lib/autoload.php to allow manual (i.e. without composer) installation.

The custom autoloader created by this commit translates class
names into filesystem locations by a simple rule: it replaces
backslashes with frontslashes, and adds ".php" on the end. Two
locations are searched for this class implementation file: first we
check under lib/, then under test/.

The existing test/bootstrap.php checked for vendor/autoload.php and
would show an error to the user if it did not exist. Now that we have
our own autoloader, we can just use that instead. So, test/bootstrap.php
was removed, and phpunit.xml.dist was pointed at the new lib/autoload.php
for its bootstrap code.

Thanks to Artur Weigandt for the implementation of the autoloader.

Author: orlitzky

lib/autoload.php

@@ -0,0 +1,31 @@
+<?php
+
+/* An autoloader for Redmine\Foo classes. This should be require()d by
+ * the user before attempting to instantiate any of the Redmine
+ * classes.
+ */
+
+spl_autoload_register(function ($class) {
+    /* All of the classes have names like "Redmine\Foo", so we need to
+     * replace the backslashes with frontslashes if we want the name
+     * to map directly to a location in the filesystem.
+     */
+    $class = str_replace('\\', '/', $class);
+
+    /* First, check under the current directory. It is important that
+     * we look here first, so that we don't waste time searching for
+     * test classes in the common case.
+     */
+    $path = dirname(__FILE__) . '/' . $class . '.php';
+    if (file_exists($path)){
+      require_once($path);
+    }
+
+    /* If we didn't find what we're looking for already, maybe it's
+     * a test class?
+     */
+    $path = dirname(__FILE__) . '/../test/' . $class . '.php';
+    if (file_exists($path)){
+      require_once($path);
+    }
+});

phpunit.xml.dist

@@ -9,7 +9,7 @@
          processIsolation="false"
          stopOnFailure="false"
          syntaxCheck="false"
-         bootstrap="test/bootstrap.php"
+         bootstrap="lib/autoload.php"
 >
     <testsuites>
         <testsuite name="php-redmine-api Test Suite">