set python3 as default python interpreter, fix whitespace and encoding issues

utils/filteroutput.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # A thin Python wrapper around addr2line, can monitor esp-open-rtos
 # output and uses gdb to convert any suitable looking hex numbers
@@ -84,7 +84,7 @@ def main():
 
     try:
         while True:
-            line = port.readline()
+            line = port.readline().decode('ISO-8859-1')
             if line == '':
                 break
             print(line.strip())
@@ -94,7 +94,8 @@ def main():
                     addr = "0x"+addr
                     # keeping addr2line and feeding it addresses on stdin didn't seem to work smoothly
                 addr2line = subprocess.check_output(["xtensa-lx106-elf-addr2line","-pfia","-e","%s" % args.elf, addr], cwd=".").strip()
-                if not addr2line.endswith(": ?? ??:0"):
+                pattern = ": ?? ??:0"
+                if not addr2line.endswith(pattern.encode()):
                     print("\n%s\n" % addr2line.strip())
     finally:
         if args.port is None: