make hierarch output format configuable

[ritchieGitHub]

As discussed in #16 and #68 there is need to make the hierarch output more flexible.
I propose:

FitsFacory.setHierarchyFormat("123");

This means that the space between HIERARCH and the first key is filled with the characters "12" and the rest of the keywords separated by "3". So the last cha is used as key separator and the rest as preffix to the HIERARCH key.

[ritchieGitHub]

I opted for the full dynamic solution now there is an interface IHierarchKeyFormatter that the user can implement and format the header keys to there wishes. There are tree default implementations, see the unit test:

    public void testHierarchAlternatives() throws HeaderCardException {
        FitsFactory.setUseHierarch(true);
        // not realy nessesary because the default:
        FitsFactory.setHierarchFormater(new StandardIHierarchKeyFormatter());
        HeaderCard headerCard = new HeaderCard("HIERARCH.TEST1.TEST2.TEST3.TEST4.TEST5.TEST6", "xy", null);
        assertEquals("HIERARCH.TEST1.TEST2.TEST3.TEST4.TEST5.TEST6", headerCard.getKey());
        assertEquals("HIERARCH TEST1 TEST2 TEST3 TEST4 TEST5 TEST6= 'xy'                              ", headerCard.toString());
        // now the formatter with all dots
        FitsFactory.setHierarchFormater(new BlanksDotHierarchKeyFormatter(1));
        assertEquals("HIERARCH.TEST1.TEST2.TEST3.TEST4.TEST5.TEST6", headerCard.getKey());
        assertEquals("HIERARCH TEST1.TEST2.TEST3.TEST4.TEST5.TEST6= 'xy'                              ", headerCard.toString());
        // now the formatter with first 2 blanks and then dots
        FitsFactory.setHierarchFormater(new BlanksDotHierarchKeyFormatter(2));
        assertEquals("HIERARCH.TEST1.TEST2.TEST3.TEST4.TEST5.TEST6", headerCard.getKey());
        assertEquals("HIERARCH  TEST1.TEST2.TEST3.TEST4.TEST5.TEST6= 'xy'                             ", headerCard.toString());

    }