add `xschem log_write text` command so erc error messages are written into errfp instead of stderr by tcl

doc/xschem_man/developer_info.html

@@ -541,6 +541,10 @@ C {verilog_timescale.sym} 1050 -100 0 0 {name=s1 timestep="1ns" precision="1ns"
 
 
 
+
+
+
+
 
 
 
@@ -991,6 +995,8 @@ C {verilog_timescale.sym} 1050 -100 0 0 {name=s1 timestep="1ns" precision="1ns"
    If 'f' is given output stderr messages to file 'f'
    if 'f' is not given and a file log is open, close log
    file and resume logging to stderr </pre>
+   <li><kbd>       log_write text</kbd></li><pre>
+   write given string to log file, so tcl can write messages on the log file</pre>
    <li><kbd>       logic_get_net net_name</kbd></li><pre>
    Get logic state of net named 'net_name'
    Returns 0, 1, 2, 3 for logic levels 0, 1, X, Z or nothing if no net found.</pre>
@@ -1639,6 +1645,7 @@ C {verilog_timescale.sym} 1050 -100 0 0 {name=s1 timestep="1ns" precision="1ns"
 
 
 
+
 
 
  </ul>

src/scheduler.c

@@ -2824,6 +2824,16 @@ int xschem(ClientData clientdata, Tcl_Interp *interp, int argc, const char * arg
       else if(argc==2 && errfp != stderr) { fclose(errfp); errfp=stderr; }
     }
 
+    /* log_write text
+     *   write given string to log file, so tcl can write messages on the log file
+     */
+    else if(!strcmp(argv[1], "log_write"))
+    {
+      if(argc > 2) {
+        dbg(0, "%s\n", argv[2]);
+      }
+    }
+
     /* logic_get_net net_name
      *   Get logic state of net named 'net_name'
      *   Returns 0, 1, 2, 3 for logic levels 0, 1, X, Z or nothing if no net found.

src/xschem.tcl

@@ -5572,7 +5572,7 @@ proc show_infotext {{err 0}} {
     if {[info exists has_x]} {
       wm deiconify .infotext
     } else {
-      puts stderr [xschem get infowindow_text]
+      xschem log_write  [xschem get infowindow_text]
     }
   }
 }