V3.2 added OnError event and bugfixes

⦁ added an OnError event, which will be called if an error occurs like trying to send data quicker than possible with the selected baudrate or an operating system reported error
⦁ fixed a bug where not checking the return value of a system all could lead to problems when the used serial device got disconnected during processing of the data received
⦁ fixed a bug where not checking the return value of a system all could lead to problems when the used serial device got disconnected during sending of data
⦁ fixed a bug where not checking the return value of a system all could lead to problems in the polling timer event