Comtool

* fix bug: crash when open serial port

* fix serial port auto find error on linux
* optimize serial port name display combobox item width

[comtool_1.7.2_Windows.7z](http://otge8q9ud.bkt.clouddn.com/comtool_1.7.2_windows.7z)

1. bin file for windows:
* [clicke me to download(comtool.7z) ](http://otge8q9ud.bkt.clouddn.com/comtool.7z)
* unzip
* run comtool.exe

2. bin file for linux
upload later
now can install by pip3:

sudo pip3 install --upgrade comtool

1. bin file for windows:
* [clicke me to download](http://otge8q9ud.bkt.clouddn.com/comtool.zip)
* unzip
* run PySerialAssistant.exe

2. bin file for linux
upload later