Avoid both tab and whitespaces for code indent

[othree]

It should be better not to use both tab and whitespaces for code indent.
One reason is tab will be explain to 8 character width in some environment (ex: github)
And cause the code looks very bad for reading.

[mroderick]

You're right, same editor, different settings on different machines :)

60c1740 should fix it :)