Ensure .cpp files are using namespace codal.

And headerfiles declare new clases in the codal namespace.

This is part of:
lancaster-university/codal-microbit-v2#240

inc/driver-models/Pin.h

@@ -60,8 +60,6 @@ DEALINGS IN THE SOFTWARE.
 
 namespace codal
 {
-    using namespace codal;
-
     /**
       * Pin capabilities enum.
       * Used to determine the capabilities of each Pin as some can only be digital, or can be both digital and analogue.

inc/types/Matrix4.h

@@ -27,6 +27,9 @@ DEALINGS IN THE SOFTWARE.
 
 #include "CodalConfig.h"
 
+namespace codal
+{
+
 /**
 * Class definition for a simple matrix, that is optimised for nx4 or 4xn matrices.
 *
@@ -198,4 +201,6 @@ inline Matrix4 Matrix4::multiplyT(Matrix4 &matrix)
     return multiply(matrix, true);
 }
 
+} // namespace codal
+
 #endif

source/driver-models/CodalUSB.cpp

@@ -38,6 +38,8 @@ DEALINGS IN THE SOFTWARE.
 #include "CodalDmesg.h"
 #include "codal_target_hal.h"
 
+using namespace codal;
+
 #define send(p, l) ctrlIn->write(p, l)
 
 CodalUSB *CodalUSB::usbInstance = NULL;

source/types/Matrix4.cpp

@@ -25,6 +25,8 @@ DEALINGS IN THE SOFTWARE.
 #include "CodalConfig.h"
 #include "Matrix4.h"
 
+using namespace codal;
+
 /**
 * Class definition for a simple matrix, optimised for n x 4 or 4 x n matrices.
 *