Merge pull request #2522 in SNORT/snort3 from ~OSERHIIE/snort3:custom_vars_wo_suffixe...

Merge pull request #2522 in SNORT/snort3 from ~OSERHIIE/snort3:custom_vars_wo_suffixes to master

Squashed commit of the following:

commit 368ff259fb2f0e37e297dd82b46ce71a2bbfc1e2
Author: Oleksandr Serhiienko <oserhiie@cisco.com>
Date:   Thu Sep 24 19:48:37 2020 +0300

    ips: move IPS variables to sub-tables which designates type

        * main: snort supports ips.variables.nets/.paths/.ports tables to specify custom variables regardless suffixes (_PATH, _PORT, _NET and _SERVER)
        * lua: update default_variables with 'nets', 'paths' and 'ports' tables in snort_defaults.lua
        * managers, parser, ports: rid-off obsolete code for variables parsing relying on the suffixes
        * snort_module: remove support for -S option
        * tools: snort2lua converts custom variables into ips.variables.nets/.paths/.ports tables
        * doc: update upgrade/differences.txt