color handling issues for the input and topic boxes

[Viqsi]

There are four issues I've found with the color handling for the Input and Topic boxes:

1. If one's text box background color is predominantly black, then turning on "Use the Text box's font and colors" will make the text cursor impossible to see (as it stays black).
2. Turning the "Use the Text box's font and colors" option OFF does not change the text color for any existing tabs; it'll stay the same. (New tabs created after the setting is turned off are unaffected.)
3. Turning on the "Use the Text box's font and colors" option also changes the background color of the topic bar, but nothing else.
4. A "reset to default color" color code in the topic bar will always change the text color to black, regardless of what the actual user-specified foreground color may be. If "Use the Text box's font and colors" is turned on and one has a black background, this results in an unreadable topic.

(Tested using XChat Azure 1.16.1 on OSX Mavericks 10.9.1)