fix wrong length calculation in IntData

[winfriedgerlach]

IntData's string length calculation is wrong for certain values. This became apparent when executing code like this:

IntData intData = new IntData();
intData.reset(54321);

char[] buf = new char[intData.length()];
for( int i=0;i<intData.length(); i++ )
            buf[i] = intData.charAt(i);

Because intData.length() is erroneously calculated as 6 instead of 5, this loop will fail with IndexOutOfBoundsException in the last iteration.

[laurentschoelens]

LGTM (even if I dont get why the 20229 in original code)
Maybe add line break in test class at the end of the file
Also add / update copyright informations in header

Thanks

[winfriedgerlach]

Added/changed copyright information, added line break

[laurentschoelens]

LGTM