Introduce CLI

main: Parse args using getopt_long() in main().

Begin implementation of a CLI. It can be launched
using ./qswiki config --cli.

Allow connecting to another instance using "attach" command.
This uses Unix domain sockets, and in the future can be used
to drop caches, reload template, etc.

Closes: #21

cliconsole.h

@@ -0,0 +1,27 @@
+#ifndef CLICONSOLE_H
+#define CLICONSOLE_H
+
+#include <iostream>
+#include <string>
+#include <vector>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include "cli.h"
+
+class CLIConsole
+{
+  private:
+	struct sockaddr_un server;
+	int sock;
+	CLIHandler *handler;
+	std::string socketPath;
+	bool attached = false;
+	std::pair<bool, std::string> send(std::string input);
+	void attach();
+
+  public:
+	CLIConsole(CLIHandler &cliHandler, std::string socketPath);
+	void startInteractive();
+};
+
+#endif // CLICONSOLE_H