Fix "bold and intensive" colors

For example, \e[0;1m\e[90m should give bold gray texts. It gave black.

Quick notes:
0 => reset all attributes
1 => use bold. In popular implementations (VTE3 & konsole), it also
changes a normal color to an intense color
90 => color0, intense; usually gray

This is already fixed in konsole:
https://github.com/KDE/konsole/commit/771b4b22289d928f77d0a3bda9762b8137f2407c

I happen to use the same function name :)

lib/Screen.cpp

@@ -419,7 +419,7 @@ void Screen::updateEffectiveRendition()
     }
 
     if (currentRendition & RE_BOLD)
-        effectiveForeground.toggleIntensive();
+        effectiveForeground.setIntensive();
 }
 
 void Screen::copyFromHistory(Character* dest, int startLine, int count) const