Make indentation in cachematrix.R consistent.

I initially marked your code 1 point off for clarity because your indentation is so inconsistent.
1) The first function uses tab for some lines and tab and space for other lines. Never mix tabs and spaces in code.
2) The second function uses a completely different indent which is smaller than the 4 space minimum mentioned in the lecture.
3) The initial comment in the second function does not follow any sensible indentation style.

After consulting with a TA who informed me that style is not part of the grading rubric, I restored your point.

Being able to follow a consistent coding style is a mark of a professional programmer.