Dji Tello: wifiMessage and lightMessage not working

[gen2thomas]

After activating and fixing issues from "errcheck" linter, the related test cases in TestHandleResponse are failing.

fast investigation:

• the "errcheck" is fine
• the test is right
• the used buffer parts are 1 byte to short, which cause a EOF problem
• the reading of one byte with a reader is most likely not needed
• the test is prepared for testing the data (see "msgAfter7") , but do not use it
• the current workaround for errcheck is to drop the return values, this should be reverted with this fix