Fix some headers

Include/RmlUi/Core/ElementInstancer.h

@@ -32,6 +32,7 @@
 #include "Traits.h"
 #include "Types.h"
 #include "Header.h"
+#include "Element.h"
 #include "Profiling.h"
 
 namespace Rml {

Source/Core/ConvolutionFilter.cpp

@@ -27,6 +27,7 @@
  */
 
 #include "../../Include/RmlUi/Core/ConvolutionFilter.h"
+#include <float.h>
 
 namespace Rml {
 namespace Core {

Source/Core/LayoutBlockBox.cpp

@@ -34,6 +34,7 @@
 #include "../../Include/RmlUi/Core/ElementScroll.h"
 #include "../../Include/RmlUi/Core/Property.h"
 #include "../../Include/RmlUi/Core/Profiling.h"
+#include <float.h>
 
 namespace Rml {
 namespace Core {

Source/Core/LayoutBlockBoxSpace.cpp

@@ -31,6 +31,7 @@
 #include "LayoutEngine.h"
 #include "../../Include/RmlUi/Core/Element.h"
 #include "../../Include/RmlUi/Core/ElementScroll.h"
+#include <float.h>
 
 namespace Rml {
 namespace Core {

Source/Core/LayoutEngine.cpp

@@ -37,6 +37,7 @@
 #include "../../Include/RmlUi/Core/Property.h"
 #include "../../Include/RmlUi/Core/Profiling.h"
 #include "../../Include/RmlUi/Core/Types.h"
+#include <float.h>
 
 namespace Rml {
 namespace Core {