Fix cursor style on blurred terminals

[parisk]

After #492 the hollow cursor style implemented in #82 broke. It displayed a filled cursor in blurred terminals, when no explicit cursor style was set (underline or bar).

This PR applies the "generic" cursor styling only when the terminal is focused.

This means that a blurred terminal will always display a hollow "block" cursor from now on.

I think that this is the best experience possible in the blurred state, since it's the same for all cursor styles and it's quite hard to think of a way to apply "blurred" state on cursor styles that are just a line (underline or bar)

[coveralls]

Coverage remained the same at 67.75% when pulling 9055bac on fix-blurred-terminal-cursor into eb25e88 on master.

[Tyriar]

Good catch, I verified the bug/fix locally.