Use line comparison algorithm.

This implementation fails on the following tests:
- *indent of a weirdly indented vendor prefixed CSS*: nothing much can be done, the problem rises because there is too few correct indents/deindents in this file;
- *indentation stats for tabs*: I believe the test is incorrect, there really are 8 tabs.
Agh, sleepy, sorry. I looked at the wrong initialization: https://github.com/sindresorhus/detect-indent/pull/11/files#diff-168726dbe96b3ce427e7fedce31bb0bcR47 Ignore me :p