API Tidy

- Remove old client ID queries, these are now built into the API keys. If a key has access to all clients, a client ID can be provided in the query.
- Small fixes to assets URI lookup
- Add read endpoint for vendors

api/v1/vendors/read.php

@@ -0,0 +1,19 @@
+<?php
+
+require_once '../validate_api_key.php';
+
+require_once '../require_get_method.php';
+
+// Specific vendor via their ID (single)
+if (isset($_GET['vendor_id'])) {
+    $id = intval($_GET['vendor_id']);
+    $sql = mysqli_query($mysqli, "SELECT * FROM vendors WHERE vendor_id = '$id' AND vendor_client_id LIKE '$client_id'");
+
+} else {
+    // All Vendors (by client ID or all in general if key permits)
+    $sql = mysqli_query($mysqli, "SELECT * FROM vendors WHERE vendor_client_id LIKE '$client_id' ORDER BY vendor_id LIMIT $limit OFFSET $offset");
+}
+
+// Output
+require_once "../read_output.php";
+