Ticket #3864: initial support of Markdown syntax highlighting.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

misc/syntax/Makefile.am

@@ -51,6 +51,7 @@ SYNTAXFILES =			\
 	m4.syntax		\
 	mail.syntax		\
 	makefile.syntax		\
+	markdown.syntax		\
 	ml.syntax		\
 	named.syntax		\
 	nemerle.syntax		\

misc/syntax/Syntax.in

@@ -286,5 +286,8 @@ include osl.syntax
 file .\*\\.([rR]|Rd|Rscript)$ R\sProgram
 include r.syntax
 
+file ..\*\\.(?i:md)$ Markdown
+include markdown.syntax
+
 file .\* unknown
 include unknown.syntax

misc/syntax/markdown.syntax

@@ -0,0 +1,35 @@
+# Markdown syntax highlighting
+
+context default lightgray
+    spellcheck
+    # links
+    keyword whole [*](*) yellow
+
+context linestart #### \n red
+    spellcheck
+
+context linestart # \n brightred
+    spellcheck
+
+context linestart > \n green
+    spellcheck
+
+context linestart \s\s\s\s \n cyan
+
+context ``` ``` cyan
+
+context `` `` cyan
+
+context ` ` cyan
+
+context \*\* \*\* brightgreen
+    spellcheck
+
+context \* \* magenta
+    spellcheck
+
+context \_\_ \_\_ brightgreen
+    spellcheck
+
+context \_ \_ magenta
+    spellcheck