Fix blinking/bold text in terminals with no color support

Before this, doing "TERM=vt100 irssi" showed all text as bold and
blinking because of a failed check of window->term->TI_colors that
was doing (value & 8) and not expecting a value of 0.

The changed lines themselves look a bit weird, but they make more sense
in the context of the original commit, 96a292d4.
Merge pull request #189 from dequis/colorless-green-ideas-blink-furiously

Fix blinking/bold text in terminals with no color support