LibVT: Implement bright color support

Previously, we only used bright colors when the bold attribute was set.
We now have the option to set it via escape sequences. We also needed to
make the bold text behavior optional, as some color schemes do weird
things with it. For example, Solarized uses it for various shades of
gray, so bold green would turn into a light shade of gray.

The following new escape sequences are supported:
- `CSI 90;m` to `CSI 97;m`: set bright foreground color
- `CSI 100;m` to `CSI 107;m`: set bright background color

Base/res/terminal-colors/Default.ini

@@ -1,7 +1,14 @@
+[Options]
+; Specifies whether bold text is displayed using bright colors.
+ShowBoldTextAsBright=true
+
+; Default text and background colors
 [Primary]
 Background=#000000
 Foreground=#ffffff
 
+; Normal named colors
+; These correspond to ANSI colors 0-7.
 [Normal]
 Black=#000000
 Red=#cc0000
@@ -12,6 +19,8 @@ Magenta=#75507b
 Cyan=#06989a
 White=#eeeec
 
+; Bright named colors
+; These correspond to ANSI colors 8-15.
 [Bright]
 Black=#555753
 Red=#ef2929