Update bundled PCRE2-library to version 10.23

Some manual changes done to the library were lost with this update.
They will be added in the next commit.

pcre2/doc/pcre2syntax.3

@@ -1,4 +1,4 @@
-.TH PCRE2SYNTAX 3 "13 June 2015" "PCRE2 10.20"
+.TH PCRE2SYNTAX 3 "23 December 2016" "PCRE2 10.23"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions (revised API)
 .SH "PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY"
@@ -81,9 +81,10 @@ it matches a literal "u".
   \eW         a "non-word" character
   \eX         a Unicode extended grapheme cluster
 .sp
-The application can lock out the use of \eC by setting the
-PCRE2_NEVER_BACKSLASH_C option. It is dangerous because it may leave the
-current matching point in the middle of a UTF-8 or UTF-16 character.
+\eC is dangerous because it may leave the current matching point in the middle
+of a UTF-8 or UTF-16 character. The application can lock out the use of \eC by
+setting the PCRE2_NEVER_BACKSLASH_C option. It is also possible to build PCRE2
+with the use of \eC permanently disabled.
 .P
 By default, \ed, \es, and \ew match only ASCII characters, even in UTF-8 mode
 or in the 16-bit and 32-bit libraries. However, if locale-specific matching is
@@ -159,6 +160,8 @@ at release 5.18.
 .SH "SCRIPT NAMES FOR \ep AND \eP"
 .rs
 .sp
+Ahom,
+Anatolian_Hieroglyphs,
 Arabic,
 Armenian,
 Avestan,
@@ -199,6 +202,7 @@ Gurmukhi,
 Han,
 Hangul,
 Hanunoo,
+Hatran,
 Hebrew,
 Hiragana,
 Imperial_Aramaic,
@@ -235,12 +239,14 @@ Miao,
 Modi,
 Mongolian,
 Mro,
+Multani,
 Myanmar,
 Nabataean,
 New_Tai_Lue,
 Nko,
 Ogham,
 Ol_Chiki,
+Old_Hungarian,
 Old_Italic,
 Old_North_Arabian,
 Old_Permic,
@@ -262,6 +268,7 @@ Saurashtra,
 Sharada,
 Shavian,
 Siddham,
+SignWriting,
 Sinhala,
 Sora_Sompeng,
 Sundanese,
@@ -421,9 +428,10 @@ appear.
   (*UCP)          set PCRE2_UCP (use Unicode properties for \ed etc)
 .sp
 Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of the
-limits set by the caller of pcre2_match(), not increase them. The application
-can lock out the use of (*UTF) and (*UCP) by setting the PCRE2_NEVER_UTF or
-PCRE2_NEVER_UCP options, respectively, at compile time.
+limits set by the caller of \fBpcre2_match()\fP or \fBpcre2_dfa_match()\fP, not
+increase them. The application can lock out the use of (*UTF) and (*UCP) by
+setting the PCRE2_NEVER_UTF or PCRE2_NEVER_UCP options, respectively, at
+compile time.
 .
 .
 .SH "NEWLINE CONVENTION"
@@ -466,6 +474,9 @@ Each top-level branch of a look behind must be of a fixed length.
   \en              reference by number (can be ambiguous)
   \egn             reference by number
   \eg{n}           reference by number
+  \eg+n            relative reference by number (PCRE2 extension)
+  \eg-n            relative reference by number
+  \eg{+n}          relative reference by number (PCRE2 extension)
   \eg{-n}          relative reference by number
   \ek<name>        reference by name (Perl)
   \ek'name'        reference by name (Perl)
@@ -504,13 +515,17 @@ Each top-level branch of a look behind must be of a fixed length.
   (?(-n)              relative reference condition
   (?(<name>)          named reference condition (Perl)
   (?('name')          named reference condition (Perl)
-  (?(name)            named reference condition (PCRE2)
+  (?(name)            named reference condition (PCRE2, deprecated)
   (?(R)               overall recursion condition
-  (?(Rn)              specific group recursion condition
-  (?(R&name)          specific recursion condition
+  (?(Rn)              specific numbered group recursion condition
+  (?(R&name)          specific named group recursion condition
   (?(DEFINE)          define subpattern for reference
   (?(VERSION[>]=n.m)  test PCRE2 version
   (?(assert)          assertion condition
+.sp
+Note the ambiguity of (?(R) and (?(Rn) which might be named reference
+conditions or recursion tests. Such a condition is interpreted as a reference
+condition if the relevant named group exists.
 .
 .
 .SH "BACKTRACKING CONTROL"
@@ -570,6 +585,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 13 June 2015
-Copyright (c) 1997-2015 University of Cambridge.
+Last updated: 23 December 2016
+Copyright (c) 1997-2016 University of Cambridge.
 .fi