+ client: add fastest_addr setting

Squashed commit of the following:

commit e47fae25f7bac950bfb452fc8f18b9c0865b08ba
Merge: a23285ec e2ddc82d
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Apr 22 19:16:01 2020 +0300

    Merge remote-tracking branch 'origin/master' into 715

commit a23285ec3ace78fe4ce19122a51ecf3e6cdd942c
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Wed Apr 22 18:30:30 2020 +0300

    Review changes

commit f80d62a0d2038ff9d070ae9e9c77c33b92232d9c
Author: ArtemBaskal <a.baskal@adguard.com>
Date:   Tue Apr 21 16:37:42 2020 +0300

    + client: Add fastest addr option

commit 9e713df80c5bf113c98794c0a20915c756a76938
Merge: e3bf4037 9b7c1181
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Tue Apr 21 16:02:03 2020 +0300

    Merge remote-tracking branch 'origin/master' into 715-fastest-addr

commit e3bf4037f49198e42bde55305d6f9077341b556a
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Tue Apr 21 15:40:49 2020 +0300

    minor

commit d6e6a823c5e51acc061b2850d362772efcb827e1
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Apr 17 17:56:24 2020 +0300

    * API changes

    . removed POST /set_upstreams_config
    . removed fields from GET /status: bootstrap_dns, upstream_dns, all_servers
    . added new fields to /dns_config and /dns_info

commit 237a452d09cc48ff8f00e81c7fd35e7828bea835
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Apr 17 16:43:13 2020 +0300

    * API: /dns_info, /dns_config: add "parallel_requests" instead of "all_servers" from /set_upstreams_config

commit 9976723b9725ed19e0cce152d1d1198b13c4acc1
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Mar 23 10:28:25 2020 +0300

    openapi

commit 6f8ea16c6332606f29095b0094d71e8a91798f82
Merge: 36e4d4e8 c8285c41
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 20 19:18:48 2020 +0300

    Merge remote-tracking branch 'origin/master' into 715-fastest-addr

commit 36e4d4e82cadeaba5a11313f0d69d66a0924c342
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 20 18:13:43 2020 +0300

    + DNS: add fastest_addr setting

client/src/__locales/en.json

@@ -1,7 +1,8 @@
 {
     "client_settings": "Client settings",
-    "example_upstream_reserved": "you can specify DNS upstream <0>for a specific domain(s)</0>",
-    "upstream_parallel": "Use parallel queries to speed up resolving by simultaneously querying all upstream servers",
+    "example_upstream_reserved": "You can specify DNS upstream <0>for the specific domain(s)</0>",
+    "upstream_parallel": "Use parallel requests to speed up resolving by simultaneously querying all upstream servers",
+    "parallel_requests": "Parallel requests",
     "bootstrap_dns": "Bootstrap DNS servers",
     "bootstrap_dns_desc": "Bootstrap DNS servers are used to resolve IP addresses of the DoH/DoT resolvers you specify as upstreams.",
     "check_dhcp_servers": "Check for DHCP servers",
@@ -453,6 +454,8 @@
     "example_rewrite_wildcard": "rewrite responses for all <0>example.org</0> subdomains.",
     "disable_ipv6": "Disable IPv6",
     "disable_ipv6_desc": "If this feature is enabled, all DNS queries for IPv6 addresses (type AAAA) will be dropped.",
+    "fastest_addr": "Fastest IP address",
+    "fastest_addr_desc": "Query all DNS servers and return the fastest IP address among all responses",
     "autofix_warning_text": "If you click \"Fix\", AdGuard Home will configure your system to use AdGuard Home DNS server.",
     "autofix_warning_list": "It will perform these tasks: <0>Deactivate system DNSStubListener</0> <0>Set DNS server address to 127.0.0.1</0> <0>Replace symbolic link target of /etc/resolv.conf with /run/systemd/resolve/resolv.conf</0> <0>Stop DNSStubListener (reload systemd-resolved service)</0>",
     "autofix_warning_result": "As a result all DNS requests from your system will be processed by AdGuard Home by default.",