Add support for constructing arrays in the logs

Currently only for constructing "safe" arrays that you want to use as
arguments to student code -- no failure messages provided if
construction fails beyond the normal java reflection exceptions.

Use

    Character[] cs = new Character[] { 'A', 'B', 'C' };
    Object arr = codeTester.constructArray(char.class, cs);
    codeTester.construct("StudentClass", arr);

An example would be if you want a log

    char[] c0 = new char[] { 'A', 'B', 'C' };
    StudentClass sc0 = new StudentClass(c0);

which is better than

    StudentClass sc0 = new StudentClass([c@a82324234);

which it shows if you just passed "new char[] { 'A', 'B', 'C' }".