cleaned up Calc header, renamed numerics folder to math

src/images/aseprite.cpp

@@ -2,7 +2,7 @@
 #include <blah/streams/filestream.h>
 #include <blah/filesystem.h>
 #include <blah/common.h>
-#include <blah/numerics/calc.h>
+#include <blah/math/calc.h>
 
 #define STBI_NO_STDIO
 #define STBI_ONLY_ZLIB

src/images/font.cpp

@@ -1,6 +1,6 @@
 #include <blah/images/font.h>
 #include <blah/streams/filestream.h>
-#include <blah/numerics/calc.h>
+#include <blah/math/calc.h>
 #include <blah/common.h>
 
 using namespace Blah;