Merge branch 'ah/userdiff-markdown'

The userdiff patterns for Markdown documents have been added.

* ah/userdiff-markdown:
  userdiff: support Markdown

userdiff.c

@@ -79,6 +79,9 @@ PATTERNS("java",
 	 "|[-+0-9.e]+[fFlL]?|0[xXbB]?[0-9a-fA-F]+[lL]?"
 	 "|[-+*/<>%&^|=!]="
 	 "|--|\\+\\+|<<=?|>>>?=?|&&|\\|\\|"),
+PATTERNS("markdown",
+	 "^ {0,3}#{1,6}[ \t].*",
+	 "[^<>= \t]+"),
 PATTERNS("matlab",
 	 /*
 	  * Octave pattern is mostly the same as matlab, except that '%%%' and