Write __repr__ for Point

Now you don't have to look at the memory address all the time
Fix test_heading_combinations() in tests

The test was requiring combinations that didn't make any sense. I've
brought some sanity into the equation.
Mark lines causing problems
Mark the places in point.py that are causing the problem

It seems that in certain cases the adjustment to the computed angle is
incorrect.
Tests pass; fixes #12

I was modifying the values incorrectly for when the point to be found
was above and to the left or below and to the right of the reference
point. Fixed that and now all tests pass.
Fixes #12

Forgot to remove FIXME tags
Merge pull request #21 from erget/12_pointHeadings

12 point headings