improve usability of ExampleBrowser

store command-line arguments in bulletDemo.txt
save/load of configuration, save demo name instead of index
add setBackgroundColor as example (background_color_red) and
mouse move/wheel speed config (mouse_wheel_multiplier and mouse_move_multiplier)
(saved after changing the demo)
default btIDebugDraw colors can be changed
b3CommandLineArgs::GetCmdLineArgument returns bool, and b3CommandLineArgs::addArgs added
fix copy/paste

src/Bullet3Common/b3CommandLineArgs.h

@@ -19,6 +19,11 @@ public:
 
 	// Constructor
 	b3CommandLineArgs(int argc, char **argv)
+	{
+		addArgs(argc,argv);
+	}
+
+	void addArgs(int argc, char**argv)
 	{
 		using namespace std;
 
@@ -39,7 +44,12 @@ public:
 	        	key = string(arg, 2, pos - 2);
 	        	val = string(arg, pos + 1, arg.length() - 1);
 	        }
-        	pairs[key] = val;
+			
+			//only add new keys, don't replace existing
+			if(pairs.find(key) == pairs.end())
+			{
+        		pairs[key] = val;
+			}
 	    }
 	}
 
@@ -54,7 +64,7 @@ public:
 	}
 
 	template <typename T>
-	void GetCmdLineArgument(const char *arg_name, T &val);
+	bool GetCmdLineArgument(const char *arg_name, T &val);
 
 	int ParsedArgc()
 	{
@@ -63,18 +73,20 @@ public:
 };
 
 template <typename T>
-inline void b3CommandLineArgs::GetCmdLineArgument(const char *arg_name, T &val)
+inline bool b3CommandLineArgs::GetCmdLineArgument(const char *arg_name, T &val)
 {
 	using namespace std;
 	map<string, string>::iterator itr;
 	if ((itr = pairs.find(arg_name)) != pairs.end()) {
 		istringstream strstream(itr->second);
 		strstream >> val;
+		return true;
     }
+	return false;
 }
 
 template <>
-inline void b3CommandLineArgs::GetCmdLineArgument<char*>(const char* arg_name, char* &val)
+inline bool b3CommandLineArgs::GetCmdLineArgument<char*>(const char* arg_name, char* &val)
 {
 	using namespace std;
 	map<string, string>::iterator itr;
@@ -83,10 +95,11 @@ inline void b3CommandLineArgs::GetCmdLineArgument<char*>(const char* arg_name, c
 		string s = itr->second;
 		val = (char*) malloc(sizeof(char) * (s.length() + 1));
 		std::strcpy(val, s.c_str());
-
+		return true;
 	} else {
     	val = NULL;
 	}
+	return false;
 }