pidgin/pidgin

Replace the manual browser opening code with gtk_show_uri_on_window

Remove the browser preference page.

replace the manual open uri code with gtk_show_uri_on_window

Testing Done:
Compiles, preference window functions properly, however talkatu doesn't handle links correctly so I couldn't test from messages or `help -> about`, but `help -> online help` worked just fine.

Reviewed at https://reviews.imfreedom.org/r/59/
#ifndef PIDGIN_ABOUT_H
#define PIDGIN_ABOUT_H
/**
* SECTION:pidginabout
* @section_id: pidgin-about
* @short_description: <filename>pidginabout.h</filename>
* @title: About Dialog
*/
#include <gtk/gtk.h>
G_BEGIN_DECLS
#define PIDGIN_TYPE_ABOUT_DIALOG (pidgin_about_dialog_get_type())
G_DECLARE_FINAL_TYPE(PidginAboutDialog, pidgin_about_dialog, PIDGIN,
ABOUT_DIALOG, GtkDialog)
GtkWidget *pidgin_about_dialog_new(void);
G_END_DECLS
#endif /* PIDGIN_ABOUT_H */