Fixed missing padding. Fixed ENC_NA/ENC_BIG_ENDIAN errors.

There was no tree items for padding in the many instances where there were
bytes added to make certain data types align on even boundaries of 2, 4, or
8 bytes. These instances now show up as "Padding" in the display.

There were many instances where ENC_NA was used for fields of more than one
byte. This wasn't noticed before because ENC_NA was ENC_BIG_ENDIAN for
historical reasons and all these fields are big endian fields.

Change-Id: Iabadd46eacc9ceb8ca85f4a5ba42b6583375c5f0
Signed-off-by: Joseph Huffman <jhuffman@codeaurora.org>
Reviewed-on: https://code.wireshark.org/review/4413
Reviewed-by: Anders Broman <a.broman58@gmail.com>