Convert (what appear to be) "4 space tabs"; Adjust editor-modelines; Do some minor reformatting.

Change-Id: Ie078c826ed38a0d682f61fb3e95450b47a9d2c31
Reviewed-on: https://code.wireshark.org/review/4499
Reviewed-by: Bill Meier <wmeier@newsguy.com>