GH-340: Improve IPv4/IPv6 regexes, extraction, and validity functions

* is_valid_ip() is now implemented as a BIF instead of in
  base/utils/addrs

* The IPv4 and IPv6 regular expressions provided by base/utils/addrs
  have been improved/corrected (previously they could possibly match
  some invalid IPv4 decimals, or various "zero compressed" IPv6 strings
  with too many hextets)

* extract_ip_addresses() should give better results as a result of
  the above two points

testing/btest/Baseline/scripts.base.utils.addrs/output

@@ -1,4 +1,4 @@
-============ test ipv4 regex
+============ test ipv4 regex (good strings)
 T
 T
 T
@@ -6,9 +6,24 @@ T
 T
 T
 T
+T
+T
+T
+T
+T
+T
+T
+============ bad ipv4 decimals
 F
 F
 F
+F
+F
+F
+============ too many ipv4 decimals
+F
+F
+============ typical looking ipv4
 T
 T
 ============ test ipv6 regex
@@ -30,6 +45,9 @@ T
 F
 F
 F
+F
+F
 ============ test extract_ip_addresses()
 [1.1.1.1, 2.2.2.2, 3.3.3.3]
 [1.1.1.1, 0:0:0:0:0:0:0:0, 3.3.3.3]
+[6:1:2::3:4:5:6]