Implement MCP JSON-RPC handling and related I/O fixes: mcploader now handles initialize, tools/list and tools/call (implements add_both_numbers) and returns JSON-RPC responses; stdio-server.send serializes object messages before writing; console logging on WScript now writes muted messages to StdErr; bump jsonrpc2 version to 0.1.7 and reformat extract(). These changes enable proper MCP capability negotiation, tool discovery and invocation over stdio.
Introduce a StdioServer module and mcploader entry script, and extend jsonrpc2 with an extract() helper. stdio-server.js provides an EventTarget-based wrapper for reading/writing via WScript stdio. mcploader.js uses the server and JsonRpc2.extract to parse incoming JSON-RPC messages and respond. Also change DEFAULT_JSONRPC2_URL to http://localhost:5555, export the new extract function, and bump jsonrpc2 version to 0.1.6.
