Added base class AIStateMachine.

This is the skeleton needed to implement classes that can be reused and
work together, which can perform asynchronous tasks (read: need to wait
for certain events before they can continue).

An example would be the task of waiting for a given inventory folder to
be read. This could then be used to improve the builtin AO
(automatically reading that folder when a notecard is dropped, and
continuing when the whole folder is read).

It's first use will be communication with a filepicker that runs
in a plugin.

indra/cwdebug/debug.cc

@@ -171,6 +171,7 @@ void stop_recording_backtraces(void)
       channel_ct gtk DDCN("GTK");		//!< This debug channel is used for output related to gtk.
       channel_ct sdl DDCN("SDL");		//!< This debug channel is used for output related to sdl locking.
       channel_ct backtrace DDCN("BACKTRACE");	//!< This debug channel is used for backtraces.
+      channel_ct statemachine DDCN("STATEMACHINE");	//!< This debug channel is used class AIStateMachine.
 
     } // namespace dc
   } // namespace DEBUGCHANNELS

indra/cwdebug/debug.h

@@ -116,6 +116,7 @@ extern CWD_API channel_ct primbackup;
 extern CWD_API channel_ct gtk;
 extern CWD_API channel_ct sdl;
 extern CWD_API channel_ct backtrace;
+extern CWD_API channel_ct statemachine;
 
 #endif