Add verbose info

[klauspost]

Add -v to display fields where padding is added.

Example:

...\encoder_options.go:14:21: struct of size 64 could be 56
Field sizes in order:
        *  concurrent int: 8:8
        *  crc bool: 1:1
        !!!  single *bool: 8:15
        *  pad int: 8:8
        *  blockSize int: 8:8
        *  windowSize int: 8:8
        *  level github.com/klauspost/compress/zstd.EncoderLevel: 8:8
        *  fullZero bool: 1:1
        *  noEntropy bool: 1:1

[klauspost]

oh. #8 is already here ;)