New font work poor under windows/XShell

[yuandong1222]

It has a fixed font size which is 24, it is too big.

[ketor]

Maybe the font format otf is not suitable for win32. Will test ttf format later.

[ketor]

Add powerline fonts repo in README.md.
I think this problem should be solved by the user.You think how?

[yuandong1222]

I will try this later.

If it works, I will close this issue.