Allow incrementing different parts of strings with modifiers

Primary increment is the right most bit, secondary is the next
rightmost. So you can increment 'A1' to 'A2' or 'B1' with
Shift-Alt-Scroll and Ctrl-Alt-Scroll respectively.

common/array_axis.cpp

@@ -23,6 +23,8 @@
 
 #include <array_axis.h>
 
+#include <increment.h>
+
 
 /**
  * @return False for schemes like 0,1...9,10
@@ -134,26 +136,9 @@ wxString ARRAY_AXIS::GetItemNumber( int n ) const
 {
     wxString        itemNum;
     const wxString& alphabet = GetAlphabet();
-
-    const bool nonUnitColsStartAt0 = schemeNonUnitColsStartAt0( m_type );
-
-    bool firstRound = true;
-    int  radix = alphabet.Length();
+    const bool      nonUnitColsStartAt0 = schemeNonUnitColsStartAt0( m_type );
 
     n = m_offset + m_step * n;
 
-    do
-    {
-        int modN = n % radix;
-
-        if( nonUnitColsStartAt0 && !firstRound )
-            modN--; // Start the "tens/hundreds/etc column" at "Ax", not "Bx"
-
-        itemNum.insert( 0, 1, alphabet[modN] );
-
-        n /= radix;
-        firstRound = false;
-    } while( n );
-
-    return itemNum;
+    return AlphabeticFromIndex( n, alphabet, nonUnitColsStartAt0 );
 }