Added initial console commands for plugins

fixed crash in plugin destructor
fixed compilation not being freed causing a crash
fixed small issues in plugin system
fixed plugin iterator not being reseted when freed and not being initialized it's current pointer.
fixed a bug where insertion of a prefixed string would not check whether a value could be set.

--HG--
extra : convert_revision : svn%3A39bc706e-5318-0410-9160-8a85361fbb7c/trunk%40221

core/sm_srvcmds.h

@@ -0,0 +1,16 @@
+#include "sourcemm_api.h"
+#include <convar.h>
+#include "sourcemod.h"
+#include "PluginSys.h"
+
+using namespace SourceMod;
+
+class ConVarAccessor : 
+	public IConCommandBaseAccessor,
+	public SMGlobalClass
+{
+public: // IConCommandBaseAccessor
+	virtual bool RegisterConCommandBase(ConCommandBase *pCommand);
+public: // SMGlobalClass
+	virtual void OnSourceModStartup(bool late);
+};