Add automatic color package loading for listings

The listings inset does automatically load the color package if any parameter
contains \color. As mentioned in bug #8066 tex2lyx needs to be aware of this,
so the \usepckage{color} is automatically skipped in these cases.

src/tex2lyx/test/test-insets.lyx.lyx

@@ -1037,7 +1037,7 @@ Listings
 
 Inline: 
 \begin_inset listings
-lstparams "language={C++}"
+lstparams "language={C++},keywordstyle={\color{green}}"
 inline true
 status collapsed
 

src/tex2lyx/test/test-insets.tex

@@ -181,7 +181,7 @@ parser test (escaped):\href{http://www.test.test}{a brace \} and another one \{
 
 \section{Listings}
 
-Inline: \lstinline[language={C++}]!int a=5;!\\
+Inline: \lstinline[language={C++},keywordstyle={\color{green}}]!int a=5;!\\
 Float:
 
 \begin{lstlisting}[caption={Example Listing float},label={lst:Example-Listing},language=Python]

src/tex2lyx/text.cpp

@@ -1154,6 +1154,8 @@ void parse_listings(Parser & p, ostream & os, Context & parent_context, bool in_
 	if (p.hasOpt()) {
 		string arg = p.verbatimOption();
 		os << "lstparams " << '"' << arg << '"' << '\n';
+		if (arg.find("\\color") != string::npos)
+	                preamble.registerAutomaticallyLoadedPackage("color");
 	}
 	if (in_line)
 		os << "inline true\n";