* add opportunity for more than one retry to _uploadReadByte
* an alternative timeout-based method to making _uploadReadByte more resilient
* move timing variables in the correct scope
* implement and use client.getTimeout instead of hard-coded timeout in _uploadReadByte
* add missing return
* some refactoring to address respecting the timeout in a potentially deadlocked connection
* fix spelling in comment
* address review comments; move impl to cpp file for getTimeout, and remove local variable for currentMillis
* remove redundant cast
* need to check for timeout outside the inner while as well
* update WebUpdate example to print something in unexpected callback condition
* update log_e messages per review comments
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