#5 GUI improvements for dark themes

[queue]

Currently the wxHexCtrl renders black text on a whitebackground. This doesn't fit well with dark window themes. This patch does the following:
1. uses wxSystemSettings::GetColour() methods to get the window color and window font color.
2. changes the color of the fonts in the popup window for tags to use the tag font color.
3. changes the tab style to wxAUI_NB_DEFAULT_STYLE which enables a close button, dragging of tabs to reorder them, and dragging of tabs to split the view vertically or horizontally.
4. Preserves the font color in the TagDialogGui

I haven't tested these on Windows yet, so i'm not entirely sure how well it works there. Also, I'm not sure if any of these go against your initial intent, so feel free to ignore or discuss any of these with me.

[queue]

dark GUI improvements patch

[Death Knight®]

I remember that I used same approach in older revisions, but changed to white background because of Mac and Windows compatibility If I remember correctly. But could handle those systems via macros...

I need to place "preferences panel", than users could select if white background or system default.

Thanks for the patch, I test it and will apply ASAP.

[Death Knight®]

okey I added but banned wxAUI_NB_DEFAULT_STYLE, instead I add properties by hand because I don't wanna see x button near of the filename. Also split feature is really good. Thanks :)