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, 16 insertions, 0 deletions

diff --git a/src/latexgen.cpp b/src/latexgen.cpp
index 50d4242..06f2baf 100644
--- a/src/latexgen.cpp
+++ b/src/latexgen.cpp
@@ -485,6 +485,10 @@ static void writeDefaultHeaderPart1(FTextStream &t)
   if (Config_getBool(LATEX_BATCHMODE))
     t << "\\batchmode\n";
 
+  // to overcome  problems wit too many open files
+  t << "\\let\\mypdfximage\\pdfximage"
+       "\\def\\pdfximage{\\immediate\\mypdfximage}";
+
   // Set document class depending on configuration
   QCString documentClass;
   if (Config_getBool(COMPACT_LATEX))
@@ -564,6 +568,18 @@ static void writeDefaultHeaderPart1(FTextStream &t)
        "\\newcommand{\\+}{\\discretionary{\\mbox{\\scriptsize$\\hookleftarrow$}}{}{}}\n"
        "\n";
 
+   QCString emojiDir=Config_getString(LATEX_EMOJI_DIRECTORY);
+   if (emojiDir.isEmpty()) emojiDir = ".";
+   emojiDir = substitute(emojiDir,"\\","/");
+   t << "% Arguments of doxygenemoji:\n"
+        "% 1) ':<text>:' form of the emoji, already \"LaTeX\"-escaped\n"
+        "% 2) unicode of the emoji inlorm like: 'U+1F603' or 'U+0031U+FE0FU+20E3' depending on the emoji\n"
+        "% 3) file name in form like: '1F603' or '0031-FE0F-20E3' depending on the emoji\n"
+	"% in case image exist use this otherwise use the ':<text>:' form\n";
+   t << "\\newcommand{\\doxygenemoji}[3]{%\n"
+        "  \\IfFileExists{" << emojiDir << "/#3.png}{\\raisebox{-0.1em}{\\includegraphics[height=0.9em]{" << emojiDir << "/#3.png}}}{#1}%\n"
+        "}\n";
+
   // Define page & text layout
   QCString paperName=Config_getEnum(PAPER_TYPE);
   // "a4wide" package is obsolete (see bug 563698)