Fix (hopefully) library dependency resolution.

Installing libs is now enabled, hardcoded.
Enable -Wall for all builds.
Fix many warnings and latent bugs.

MultiMC.cpp

@@ -190,6 +190,9 @@ MultiMC::MultiMC(int &argc, char **argv) : QApplication(argc, argv)
 		case QNetworkProxy::FtpCachingProxy:
 			proxyDesc = "FTP caching: ";
 			break;
+		default:
+			proxyDesc = "DERP proxy: ";
+			break;
 		}
 		proxyDesc += QString("%3@%1:%2 pass %4")
 						 .arg(proxy.hostName())