BibTeX: accept "." and "/" as parts of a bib entry

Close #3823.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

Units/parser-bibtex.r/bib-simple.d/expected.tags

@@ -15,3 +15,4 @@ john_doe	input.bib	/^@string{john_doe = "Prof. Dr. John Doe"}$/;"	s	language:Bib
 xx_thoughts	input.bib	/^@unpublished{xx_thoughts,$/;"	u	language:BibTeX
 hicks:2001	input.bib	/^@Book{hicks:2001,$/;"	b	language:BibTeX
 knuthwebsite	input.bib	/^@online{knuthwebsite,$/;"	V	language:BibLaTeX
+10.1145/605432.605407	input.bib	/^@Article{10.1145\/605432.605407,$/;"	a	language:BibTeX

Units/parser-bibtex.r/bib-simple.d/input.bib

@@ -117,3 +117,10 @@ @online{knuthwebsite
     url       = "http://www-cs-faculty.stanford.edu/~uno/abcde.html",
     keywords  = "latex,knuth"
 }
+
+@Comment Taken from https://github.com/universal-ctags/ctags/issues/3802#issuecomment-1723511773
+@Comment submitted by @andregpss (André Silva)
+@Article{10.1145/605432.605407,
+author = {Levis, Philip and Culler, David},
+title = {Mat'{e}: A Tiny Virtual Machine for Sensor Networks},
+year = {2002} }

parsers/bibtex.c

@@ -34,7 +34,7 @@
 #define isType(token,t)		(bool) ((token)->type == (t))
 #define isKeyword(token,k)	(bool) ((token)->keyword == (k))
 #define isIdentChar(c) \
-	(isalpha (c) || isdigit (c) || (c) == '_' || (c) == '-' || (c) == '+' || (c) == ':')
+	(isalpha (c) || isdigit (c) || (c) == '_' || (c) == '-' || (c) == '+' || (c) == ':' || (c) == '.' || (c) == '/')
 
 /*
  *	 DATA DECLARATIONS