pidgin/pidgin

Greatly simplify the nick color generation and properly detect dark themes.

Instead of randomly adjusting colors based on some seed colors we now hash a user's name and use the first 2 bytes of the digest to determine the hue to color their nick. We then adjust it according to the background color.

This isn't perfect as you can see in the screen shot, but there are some tweaks we can do later to account for that. I skipped them for now as this gets us 90% of the way there with like 50% of the work.

Testing Done:
Compiled and ran locally with Adwaita, Adwaita-Dark, and Arc-Dark themes.

Bugs closed: PIDGIN-17463

Reviewed at https://reviews.imfreedom.org/r/423/
/*
* Purple - Internet Messaging Library
* Copyright (C) Pidgin Developers <devel@pidgin.im>
*
* Purple is the legal property of its developers, whose names are too numerous
* to list here. Please refer to the COPYRIGHT file distributed with this
* source distribution.
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* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
*/
#ifndef PURPLE_PURPLE_H
#define PURPLE_PURPLE_H
#ifndef __GI_SCANNER__ /* hide this bit from g-ir-scanner */
# ifdef PURPLE_COMPILATION
# error "libpurple source files should not be including purple.h"
# endif /* PURPLE_COMPILATION */
#endif /* __GI_SCANNER__ */
#include <glib.h>
#ifndef PURPLE_GLOBAL_HEADER_INSIDE
# define PURPLE_GLOBAL_HEADER_INSIDE
#endif /* PURPLE_GLOBAL_HEADER_INSIDE */
@PURPLE_H_INCLUDES@
#undef PURPLE_GLOBAL_HEADER_INSIDE
#endif /* PURPLE_PURPLE_H */