TraceAPI plugin

This was originally intended as a (more or less) complete example of a Metamod plugin. It catches every call available to it (dll routines both before and after the game, as well as engine functions both before and after the engine).

Because it catches every routine, I figured I'd give it the ability to log when given routines are called, so it became an "api tracing" plugin. :)

This can actually be useful for tracking the operation of the HL engine, as well as that of a particular HL game mod.

It recognizes the following server cvars:

   // Tracing debug levels; higher values log increasingly frequent routines.
   // Currently 0-50.  See "api_info.cpp" for the debug levels of various
   // functions.

   // Trace level for dllapi routines.

   // Trace level for "new" dllapi routines.

   // Trace level for engine functions.

   // Enable unlimited trace logging.  By default (as of v1.06), it only
   // logs _one_ trace message per second, to keep from overwhelming the
   // server.  Set to "1" to enable unlimited logging.  (Default "0")

   // General debug level, independent of trace levels.  Not currently used.

and the following server commands:

   // Enable tracing of a given routine, independent of "trace_*" level.
   // See the list of routine names in "api_info.cpp".  Case is insignificant.
   trace set <APIroutine>

   // Disable tracing of a given routine, iff previously enabled with "trace".
   // Doesn't affect routines being logged via "trace_*" level.
   trace unset <APIroutine>

   // Show the routines being traced.
   trace show

   // List the various routines that can be traced.
   trace list dllapi
   trace list newapi
   trace list engine
   trace list all

   // Prints out version/date/etc.
   trace version

Note the information it logs on each routine invocation is, at the moment, relatively minimal. I included information that seemed obvious (args for a ClientCommand, etc), and I've added info for other routines as I've come across a need. Most routines I still know too little about to log any particular information (CreateBaseline, etc). Feel free to add information that you're interested in to the log messages in the routines; the examples should be pretty self-explanatory. I'd be interested in knowing as well, for adding it to the distribution code.