firewall: resync with master

firewall: resync with master

Update to latest Git HEAD in order to import a number of fixes and other
improvements:

a4d98ae options: remove stray continue statement
3d2c18a options: improve handling of negations when parsing space separated values
0e5dd73 iptables: support -i, -o, -s and -d in option extra
4cb06c7 ubus: increase ubus network interface dump timeout
e5dfc82 iptables: add exception handling
f625954 firewall3: add check_snat() function
7d3d9dc firewall3: display the section type for UBUS rules
53ef9f1 firewall3: add UBUS support for include scripts
5cd4af4 firewall3: add UBUS support for ipset sections
02d6832 firewall3: add UBUS support for forwarding sections
0a7d36d firewall3: add UBUS support for redirect sections
d44f418 firewall3: add fw3_attr_parse_name_type() function
e264c8e firewall3: replace warn_rule() by warn_section()
6039c7f firewall3: check the return value of fw3_parse_options()
c328d1f build: use -Wno-format-truncation instead of -Wno-error=format-truncation
e06e537 utils: replace sprintf use with snprintf to avoid overflows
533f834 build: disable the format-truncation warning error to fix gcc 7 build errors
e751cde zones: drop outgoing invalid traffic in masqueraded zones
d596f72 rules: fix UCI context in error reporting
1d0564c ubus: fix interface name and proto lookup
82ccd9e firewall3: fix handling of UTC times
1949e0c iptables: support xtables API > 11

Fixes FS#548, FS#640, FS#806, FS#811.

Ref: https://forum.lede-project.org/t/nat-leakage-on-tl-wr1043nd-v4/1712

Signed-off-by: Jo-Philipp Wich <jo@mein.io>