deprecate fluid_synth_error()

doc/fluidsynth-v20-devdoc.txt

@@ -21,6 +21,7 @@ All the source code examples in this document are in the public domain; you can
 
 - \ref Disclaimer
 - \ref Introduction
+- \ref NewIn2_0_2
 - \ref NewIn2_0_0
 - \ref CreatingSettings 
 - \ref CreatingSynth 
@@ -60,6 +61,11 @@ What is FluidSynth?
 
 - FluidSynth is open source, in active development. For more details, take a look at http://www.fluidsynth.org
 
+
+\section NewIn2_0_2 Whats new in 2.0.2?
+
+- fluid_synth_error() has been deprecated, use fluid_set_log_function() to interfere log messages
+
 \section NewIn2_0_0 Whats new in 2.0.0?
 
 FluidSynths major version was bumped. The API was reworked, deprecated functions were removed.

include/fluidsynth/synth.h

@@ -233,7 +233,7 @@ FLUIDSYNTH_API int fluid_synth_tuning_dump(fluid_synth_t *synth, int bank, int p
 /* Misc */
 
 FLUIDSYNTH_API double fluid_synth_get_cpu_load(fluid_synth_t *synth);
-FLUIDSYNTH_API const char *fluid_synth_error(fluid_synth_t *synth);
+FLUID_DEPRECATED FLUIDSYNTH_API const char *fluid_synth_error(fluid_synth_t *synth);
 
 
 /* Default modulators */

src/synth/fluid_synth.c

@@ -1110,6 +1110,8 @@ delete_fluid_synth(fluid_synth_t *synth)
  * @return Pointer to string of last error message.  Valid until the same
  *   calling thread calls another FluidSynth function which fails.  String is
  *   internal and should not be modified or freed.
+ * @deprecated This function is not thread-safe and does not work with multiple synths.
+ * It has been deprecated. It may return "" in a future release and will eventually be removed.
  */
 /* FIXME - The error messages are not thread-safe, yet. They are still stored
  * in a global message buffer (see fluid_sys.c). */