issue_6517: Emoji support

Added issue support for the different output types.

- Sources of the emoji
  - based on the Unicode definition v11.0:
    - https://unicode.org/emoji/charts/full-emoji-list.html
    - http://www.unicode.org/emoji/charts/full-emoji-modifiers.html
  - github definition list:
    - https://api.github.com/emojis

- Input of emoji: :<test>: with the restriction that direct after the opening colon and direct before the closing colon no space is allowed
  - doctokinizer.l, adding detection of emoji and new command `\:`
  - doktokinizer.h, adding "word" type  TK_EMOJI
  - docparser.* handling of new "word" type TK_EMOJI (analogous to HTML Entities), handling of new command `\:`
  - cmdmapper,cpp, cmdmapper.h, adding new command `\:`
  - htmlentity.cpp, adding new definition required for new command `\:`

- Emoji
  - emoji.cpp, emoji.h, class for handling emoji analogous to HTML Entities, including small directions on how to update the code when a new emoji is defined. Not everything is converted to lowercase for comparison and accents are removed.
  - doxygen.cpp possibility to create list of supported emoji

- handling emoji for output types (analogous to HTML Entities), see documentation for different output types
  - docparser.h, *docvisitor.*
  - rtfdocvisitor.* converting output to UTF-16 (based on http://scruss.com/blog/2017/03/12/in-the-unlikely-event-you-need-to-represent-emoji-in-rtf-using-perl/)
  - latexdocvisitor.*, handling arguments for emoji in output (see also latexgen.cpp for meaning of the arguments of doxygenemoji).
  - latexgen.cpp, adding new latex command for doxygen (doxygenemoji) and prevent too many open file (code before documentclass)
  - config.xml, definition of `LATEX_EMOJI_DIRECTORY` with path to images required for LaTeX output

- Documentation:
   - emojisup.doc, user description
   - commands.doc, description of new command `\:`
   - index.doc, reference to emoji chapter
   - xmlcmds.doc, adjust reference to next chapter as a new chapter is added
   - Doxyfile*, adding emoji chapter

Build system
  - CMakeLists.txt adding new files

1 files changed, 43 insertions, 0 deletions

diff --git a/src/rtfdocvisitor.cpp b/src/rtfdocvisitor.cpp
index 7fbfdc8..941b937 100644
--- a/src/rtfdocvisitor.cpp
+++ b/src/rtfdocvisitor.cpp
@@ -34,6 +34,7 @@
 #include "filedef.h"
 #include "config.h"
 #include "htmlentity.h"
+#include "emoji.h"
 #include "plantuml.h"
 
 //#define DBG_RTF(x) m_t << x
@@ -136,6 +137,48 @@ void RTFDocVisitor::visit(DocSymbol *s)
   m_lastIsPara=FALSE;
 }
 
+void RTFDocVisitor::visit(DocEmoji *s)
+{
+  if (m_hide) return;
+  DBG_RTF("{\\comment RTFDocVisitor::visit(DocEmoji)}\n");
+  const char *res = EmojiEntityMapper::instance()->rtf(s->emoji());
+  if (res)
+  {
+    const char *p = res;
+    int val = 0;
+    int val1 = 0;
+    while (*p)
+    {
+      switch(*p)
+      {
+        case '&': case '#': case 'x':
+          break;
+        case ';':
+	  val1 = val;
+	  val = 0xd800 + ( ( val1 - 0x10000 ) & 0xffc00 ) / 0x400 - 0x10000;
+          m_t << "\\u" << val << "?";
+          val = 0xdC00 + ( ( val1 - 0x10000 ) & 0x3ff ) - 0x10000 ;
+          m_t << "\\u" << val << "?";
+          val = 0;
+          break;
+        case '0': case '1': case '2': case '3': case '4':
+        case '5': case '6': case '7': case '8': case '9':
+          val = val * 16 + *p - '0';
+          break;
+        case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
+          val = val * 16 + *p - 'a' + 10;
+          break;
+      }
+      p++;
+    }
+  }
+  else
+  {
+    err("RTF: non supported Emoji-entity found: %s\n",EmojiEntityMapper::instance()->html(s->emoji()));
+  }
+  m_lastIsPara=FALSE;
+}
+
 void RTFDocVisitor::visit(DocURL *u)
 {
   if (m_hide) return;