core: move nick coloring from irc plugin to core (closes #262)

Options moved from irc.conf to weechat.conf:

* "irc.look.nick_color_force" moved to "weechat.look.nick_color_force"
* "irc.look.nick_color_hash" moved to "weechat.look.nick_color_hash"
* "irc.look.nick_color_stop_chars" moved to
  "weechat.look.nick_color_stop_chars"

New info (for API function "info_get"):

* "nick_color" (replaces "irc_nick_color")
* "nick_color_name" (replaced "irc_nick_color_name")

Info "irc_nick_color" and "irc_nick_color_name" are now deprecated.

And a bug has been fixed in nick coloring: stop chars are removed before
looking at a forced color.

src/plugins/plugin-api.c

@@ -59,6 +59,7 @@
 #include "../gui/gui-key.h"
 #include "../gui/gui-layout.h"
 #include "../gui/gui-line.h"
+#include "../gui/gui-nick.h"
 #include "../gui/gui-nicklist.h"
 #include "../gui/gui-window.h"
 #include "plugin.h"
@@ -785,6 +786,40 @@ plugin_api_info_color_rgb2term_cb (const void *pointer, void *data,
     return value;
 }
 
+/*
+ * Returns nick color code for a nickname.
+ */
+
+const char *
+plugin_api_info_nick_color_cb (const void *pointer, void *data,
+                               const char *info_name,
+                               const char *arguments)
+{
+    /* make C compiler happy */
+    (void) pointer;
+    (void) data;
+    (void) info_name;
+
+    return gui_nick_find_color (arguments);
+}
+
+/*
+ * Returns nick color name for a nickname.
+ */
+
+const char *
+plugin_api_info_nick_color_name_cb (const void *pointer, void *data,
+                                    const char *info_name,
+                                    const char *arguments)
+{
+    /* make C compiler happy */
+    (void) pointer;
+    (void) data;
+    (void) info_name;
+
+    return gui_nick_find_color_name (arguments);
+}
+
 /*
  * Returns WeeChat infolist "bar".
  *
@@ -1855,6 +1890,14 @@ plugin_api_init ()
                N_("RGB color converted to terminal color (0-255)"),
                N_("rgb,limit (limit is optional and is set to 256 by default)"),
                &plugin_api_info_color_rgb2term_cb, NULL, NULL);
+    hook_info (NULL, "nick_color",
+               N_("get nick color code"),
+               N_("nickname"),
+               &plugin_api_info_nick_color_cb, NULL, NULL);
+    hook_info (NULL, "nick_color_name",
+               N_("get nick color name"),
+               N_("nickname"),
+               &plugin_api_info_nick_color_name_cb, NULL, NULL);
 
     /* WeeChat core infolist hooks */
     hook_infolist (NULL, "bar",