Merge branch 'bugfix/idf_monitor' into 'master'

idf_monitor: Small fixes (baud rate, EOL, /dev/tty.X on macOS, Ctrl-T on failure)

* "make monitor" now passed the configured baud rate.
  Closes #436 https://github.com/espressif/esp-idf/issues/436
* Pass toolchain prefix from sdkconfig into monitor tool
* Allow setting EOL in idf_monitor.py, use CRLF by default
* Detect if /dev/tty.X is used on macOS, warn and replace with /dev/cu.X
* If a build fails or gdb exits, ignore Ctrl-T (allowing Ctrl-T Ctrl-A/F to be same key sequence everywhere)
* Add a note about winpty on Windows.
  Ref https://github.com/espressif/esp-idf/commit/02fdf8271de3a6db2ab9d4d6f023c160c84ebdbe#commitcomment-21369196
* Fix problems with Console.cancel() not existing in older pyserial
* Print more user-friendly symbols for "start of iram" and "start of flash"

See merge request !594

components/esp32/ld/esp32.common.ld

@@ -71,6 +71,10 @@ SECTIONS
     *(.init.literal)
     *(.init)
     _init_end = ABSOLUTE(.);
+
+    /* This goes here, not at top of linker script, so addr2line finds it last,
+       and uses it in preference to the first symbol in IRAM */
+    _iram_start = ABSOLUTE(0);
   } > iram0_0_seg
 
   .iram0.text :
@@ -193,5 +197,11 @@ SECTIONS
     *(.gnu.version)
     _text_end = ABSOLUTE(.);
     _etext = .;
+
+    /* Similar to _iram_start, this symbol goes here so it is
+       resolved by addr2line in preference to the first symbol in
+       the flash.text segment.
+    */
+    _flash_cache_start = ABSOLUTE(0);
   } >iram0_2_seg
 }