List of changes:
* Deprecated public API wifi_prov_mgr_event_handler() and added private function wifi_prov_mgr_event_handler_internal(), registered with the default event loop for catching WIFI and IP system events
1. resend eb which are pending in g_ic.tx_buf due to channel switch.
2. add lock for mgmg/xon/bcast to protect send from user flush.
3. softap: add check if secondary offset is correct when start softap.
4. softap: in inactive timer handler, add check if child bss is removed to avoid removing it again.
5. disable A-MPDU for non-root.
6. fix reusing a freed eb.
7. fix when node becomes root, it does not record assoc value to nvs.
8. discard unnecessary forwarded group packets.
9. fix toDS state is not updated in time.
10. fix s_sta_cnx_times is not cleared when deinit causes root sends ADD annoucement.
11. root: increase beacon timeout time from 6 seconds to 15 seconds to delay initiation of reconnection.
12. add esp_mesh_get_tsf_time to return TSF time.
13. send the whole routing table multi-times.
14. clear candidate settings if not receive candidate beacon within 8 seconds.
Other changes:
* Command line argument name and descriptions updated and formatted
* Some exception messages updated for clarity
* READMEs updated for tool and all provisioning examples
* Minor update in example test scripts due to change in esp_prov.get_transport() API
* Transport_HTTP now forces connect on initialization
If bluetooth modem sleep is enabled and "External 32kHz crystal" is used as bluetooth sleep clock, the power management lock "ESP_PM_NO_LIGHT_SLEEP" in bluetooth is released for the periods of time when Bluetooth enters modem sleep. In this case automatic light sleep is allowed.
use `subprocess.Popen` when catch TypeError:
```
Traceback (most recent call last):
File "tools/idf_tools.py", line 1249, in <module>
main(sys.argv[1:])
File "tools/idf_tools.py", line 1245, in main
action_func(args)
File "tools/idf_tools.py", line 1038, in action_install
tool_obj.find_installed_versions()
File "tools/idf_tools.py", line 468, in find_installed_versions
ver_str = self.check_version()
File "tools/idf_tools.py", line 426, in check_version
version_cmd_result = run_cmd_check_output(cmd, None, extra_paths)
File "tools/idf_tools.py", line 176, in run_cmd_check_output
result = subprocess.run(cmd, capture_output=True, check=True, input=input_text)
File "/opt/pyenv/pyenv-1.2.6/versions/3.5.5/lib/python3.5/subprocess.py", line 383, in run
with Popen(*popenargs, **kwargs) as process:
TypeError: __init__() got an unexpected keyword argument 'capture_output'
```
1. Moved get-started files, 7 documents in total, from get-started-cmake folder to hw-reference folder;
2. Deleted get-started files, 7 documents in total, in get-started folder;
3. Updated links in get-started-cmake/index.rst and in get-started/index.rst;
4. Modified descriptions for build system in these files.
