rename files, fix Linux build

Demos3/AllBullet2Demos/premake4.lua

@@ -26,6 +26,8 @@
 		"../bullet2/FeatherstoneMultiBodyDemo/BulletMultiBodyDemos.h",
 		"../bullet2/BasicDemo/BasicDemo.cpp",
 		"../bullet2/BasicDemo/BasicDemo.h",
+		"../bullet2/RagdollDemo/RagdollDemo.cpp",
+		"../bullet2/RagdollDemo/RagdollDemo.h",
 		"../../src/Bullet3Common/**.cpp",
  		"../../src/Bullet3Common/**.h",
 		"../../btgui/Timing/b3Clock.cpp",
@@ -34,6 +36,7 @@
 		"../GpuDemos/gwenUserInterface.h"
 		}
 
+if os.is("Linux") then links{"X11"} end
 if os.is("MacOSX") then
                         links{"Cocoa.framework"}
 end

Demos3/SimpleOpenGL3/premake4.lua

@@ -26,6 +26,7 @@
 		"../../btgui/Timing/b3Clock.h"
 
 		}
+if os.is("Linux") then links {"X11"} end
 
 if os.is("MacOSX") then
                         links{"Cocoa.framework"}