Add initial support for chained exception inspection
Prepending exception frame list with previous exception's topmost part that matters for #43
Adding PHPDoc for Frame::equals
Checking if one of comparing Frames is an Unknown frame to keep them separate
Merge pull request #132 from synchrone/feature/exception-chaining

Prepending frames from previousException to inspected exception
Minor cleanup to Exception\Frame::equals
Merge remote-tracking branch 'origin/feature/exception-chaining'

Conflicts:
	src/Whoops/Exception/Inspector.php