Fix (hopefully) library dependency resolution.

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

logic/OneSixUpdate.cpp

@@ -198,7 +198,6 @@ void OneSixUpdate::jarlibStart()
 
 	auto metacache = MMC->metacache();
 	QList<ForgeXzDownloadPtr> ForgeLibs;
-	bool already_forge_xz = false;
 	for (auto lib : libs)
 	{
 		if (lib->hint() == "local")