automatic vendor path detection with composer-installer

[davidverholen]

taken from magento2 functionality:

if the magento composer installer would add a file which returns the vendor path
(app/etc/vendor_path.php in magento2)
this module could add the composer autoloader automatically.

It would have to require (or maybe suggest) the magento composer installer in a version which supports this)

[barryvdh]

Looks like an interesting idea, shouldn't be too hard to implement here.

protected function getComposerVendorPath(){
    $baseDir = Mage::getBaseDir();

    if (file_exists($baseDir .'/app/etc/vendor_path.php')) {
        $vendorDir = require $baseDir .'/app/etc/vendor_path.php';
        return "{$baseDir}/{$vendorDir}";
    } else {
        $node = Mage::getConfig()->getNode(self::CONFIG_PATH_COMPOSER_VENDOR_PATH);
        $path = str_replace( '{{root_dir}}', $baseDir, $node);
        return $path;
    }
}

It probably doesn't matter much, but it does make it easier to write the path to a file.