Amend AudioFileReader_open() by expNumChannels, return error in case of mismatch

The current encoder application gets the number of input channels signaled via commandline argument. In case of WAVE file reading, the number of channels in additionally available via the WAVE header, similar as for the sampling rate.

In case of sampling rate, AudioFileReader_open() checks whether the expected sampling rate matches the sampling rate as signaled in the WAVE header. In case of mismatch, an error is returned.

In case of number of input channels, this check is missing.

It is proposed to amend AudioFileReader_open() by also checking against expNumChannels, i.e. the expected number of input channels as derived from the commandline input.

Problem: The framework currently provides this information only after configuring the core-coder. I could imagine that this information could be additionally derived in parseCmdlIVAS_enc() and stored in the EncArgumentsstruct.