Added C plugin code from plugins branch

src/plugins/callbacks.h

@@ -0,0 +1,68 @@
+/*
+ * callbacks.h
+ *
+ * Copyright (C) 2012 - 2015 James Booth <boothj5@gmail.com>
+ *
+ * This file is part of Profanity.
+ *
+ * Profanity is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Profanity is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Profanity.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link the code of portions of this program with the OpenSSL library under
+ * certain conditions as described in each individual source file, and
+ * distribute linked combinations including the two.
+ *
+ * You must obey the GNU General Public License in all respects for all of the
+ * code used other than OpenSSL. If you modify file(s) with this exception, you
+ * may extend this exception to your version of the file(s), but you are not
+ * obligated to do so. If you do not wish to do so, delete this exception
+ * statement from your version. If you delete this exception statement from all
+ * source files in the program, then also delete it here.
+ *
+ */
+
+#ifndef CALLBACKS_H
+#define CALLBACKS_H
+
+#include <glib.h>
+
+typedef struct p_command {
+    const char *command_name;
+    int min_args;
+    int max_args;
+    const char *usage;
+    const char *short_help;
+    const char *long_help;
+    void *callback;
+    void (*callback_func)(struct p_command *command, gchar **args);
+} PluginCommand;
+
+typedef struct p_timed_function {
+    void *callback;
+    void (*callback_func)(struct p_timed_function *timed_function);
+    int interval_seconds;
+    GTimer *timer;
+} PluginTimedFunction;
+
+typedef struct p_window_input_callback {
+    void *callback;
+    void (*callback_func)(struct p_window_input_callback *window_callback, const char *tag, const char * const line);
+} PluginWindowCallback;
+
+void callbacks_add_command(PluginCommand *command);
+void callbacks_add_timed(PluginTimedFunction *timed_function);
+void callbacks_add_window_handler(const char *tag, PluginWindowCallback *window_callback);
+void * callbacks_get_window_handler(const char *tag);
+
+#endif