1) Added natives: HookConVarChange(), UnhookConVarChange(), and GetConVarName()
2) Fixed bug(s) where ConVar handles were being created when they didn't need to be
3) Fixed bug where convars not created by SourceMod would be unregistered
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extra : convert_revision : svn%3A39bc706e-5318-0410-9160-8a85361fbb7c/trunk%40471