RxValue Electron

Adds IPC classes that work similar to Electron's builtin ipcMain and ipcRenderer.

For IpcMain, the callback passed to handle(funcitonName, handle) should return an RxValue or an RxList. A channel will be opened to the client, the RxValue will be subscribed to, and new values will automatically be piped to the client. The channel will be closed and the RxValue unsubscribed when an "unsubscribe" message is sent from the client.

For IpcRender, simpy call getValue(functionName, ...args) or getList(functionName, ...args). An RxValue or RxList will be returned. Upon subscribing to the returned RxValue, a channel will be opened to the server, the function will be invoked on the server, and all values from the server will be piped to the return RxValue. Upon unsubscribing from the RxValue, an "unsubscribe" message will be sent to the server, and the channel will be closed. The channel will not be open upon further subscriptions. Therefore, once unsubscribed, the RxValue will be dead.