tex2lyx/Preamble.cpp: revert a part of [041a3add/lyxgit]

There is a general problem of tex2lyx handling theorems. it is not sufficient to cure only one instance as I did. For more info see bug #9561.

Update the references accordingly.

src/tex2lyx/Preamble.cpp

@@ -1692,17 +1692,8 @@ void Preamble::parse(Parser & p, string const & forceclass,
 
 			add_known_theorem(name, opt1, !opt2.empty(), from_utf8(complete));
 
-			// we know that our theorem module already add automatically some
-			// theorem definition. They must not be output in the preamble to
-			// avoid LaTeX errors about redefinitions
-			if (complete == "\\newtheorem{thm}{\\protect\\theoremname}")
-				in_lyx_preamble = true;
-			else
-				in_lyx_preamble = false;
-
 			if (!in_lyx_preamble)
-				h_preamble << "\\newtheorem{" << name << '}'
+				h_preamble << complete;
-				           << opt1 << opt2 << '{' << body << '}' << opt3;
 		}
 
 		else if (t.cs() == "def") {

src/tex2lyx/test/test-modules.lyx.lyx

@@ -9,6 +9,7 @@
 \numberwithin{figure}{section} %% Comment out for sequentially-numbered
 \providecommand{\theoremname}{Theorem}
 \theoremstyle{plain}
+\newtheorem{thm}{\protect\theoremname}\theoremstyle{plain}
 \newtheorem{lem}[thm]{Lemma}
 
 \usepackage{babel}

src/tex2lyx/test/test-refstyle-theorems.lyx.lyx

@@ -38,6 +38,7 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands.
 \theoremstyle{plain}
+\newtheorem{thm}{\protect\theoremname}\theoremstyle{plain}
 \newtheorem{lem}[thm]{\protect\lemmaname}\theoremstyle{plain}
 \newtheorem{cor}[thm]{\protect\corollaryname}\theoremstyle{plain}
 \newtheorem{prop}[thm]{\protect\propositionname}\theoremstyle{plain}