bugfix: Working for multiline blocks

Up until now, the code would only work on single-line code.  Any
multi-line stuff (functions, loops, etc) would fail.  Octave's eval
command is very different than the interactive environment.  It treats
each eval as its own complete script.

The solution was to try to recognize a code "block", in order to
execute it as a whole.  To avoid writing a parser/lexer, I use a simple
indentation rule.  This works nicely, but it means that some octave
code will not work.  Examples that won't work:

    function y = foo(x)
        y = x + 2;
        endfunction

    a = [1 2 3
    4 5 6];

    a = [
      1 2 3
      4 5 6
    ]

    for i=1:5
    for j=1:5
        a(i) = i+j;
    endfor
    endfor

	modified:   README.md
	modified:   example_script.m
	modified:   show_your_work.m