Added ability for candatagrid to show the currently used bits in gray.

Used in signal editor to help make it easier to know what bits are
used. Added single and double precision float code where appropriate.
They weren't supported at all before. But, that code isn't really
tested yet. Added support for multiplexed signals. Most all the code
for the UI is done and some of the backend but it isn't hooked into
the actual signal processing code just yet. Updated program version
number.

candatagrid.h

@@ -17,6 +17,7 @@ public:
     void paintEvent(QPaintEvent *event);
     void setReference(unsigned char *, bool);
     void updateData(unsigned char *, bool);
+    void setUsed(unsigned char *, bool);
     void saveImage(QString filename, int width, int height);
 
 protected:
@@ -29,6 +30,7 @@ private:
     Ui::CANDataGrid *ui;
     unsigned char refData[8];
     unsigned char data[8];
+    unsigned char usedData[8];
     QPoint upperLeft, gridSize;
 };