api: cl+sv: make an exported function in HL modding bases that will return compile-time tables with the required content

[SmileyAG]

This is needed in the future to support BXT by modders themself in their SDKs

Most likely this will be an exported global variable with our custom structure, in which we will store the following elements:

• classname (e.g. CBasePlayer)
• name (e.g. m_rgAmmoLast)
• offset (e.g. 4919 (0x1337 in hex))
• size (e.g. 32)

Macro for export:

#ifdef _WIN32
#define DLLEXPORT __declspec(dllexport)
#else
#define DLLEXPORT __attribute__ ((visibility("default")))
#endif

[SmileyAG]

While I was doing #494 issue, I thought that it would be possible to simply export save data of classes and get access to them by symbols, which would to solve issue of server-side offsets for half that surely

Although we still have to came up with concept of our linked list for the rest stuff and I think it should look like this:

typedef struct bxt_data_s
{
    char *classname; // CBasePlayer
    char *name; // m_rgAmmoLast
    unsigned int offset; // 0x1337
    unsigned int size; // 32
    BXT_FIELDTYPE type; // FIELD_INTEGER
    struct bxt_data_s *next;
} bxt_data_t;

BXT_FIELDTYPE is inherited from FIELDTYPE:

BunnymodXT/HLSDK/engine/eiface.h

Lines 366 to 388 in 1196334

	typedef enum _fieldtypes
	{
	FIELD_FLOAT = 0, // Any floating point value
	FIELD_STRING, // A string ID (return from ALLOC_STRING)
	FIELD_ENTITY, // An entity offset (EOFFSET)
	FIELD_CLASSPTR, // CBaseEntity *
	FIELD_EHANDLE, // Entity handle
	FIELD_EVARS, // EVARS *
	FIELD_EDICT, // edict_t *, or edict_t * (same thing)
	FIELD_VECTOR, // Any vector
	FIELD_POSITION_VECTOR, // A world coordinate (these are fixed up across level transitions automagically)
	FIELD_POINTER, // Arbitrary data pointer... to be removed, use an array of FIELD_CHARACTER
	FIELD_INTEGER, // Any integer or enum
	FIELD_FUNCTION, // A class function pointer (Think, Use, etc)
	FIELD_BOOLEAN, // boolean, implemented as an int, I may use this as a hint for compression
	FIELD_SHORT, // 2 byte integer
	FIELD_CHARACTER, // a byte
	FIELD_TIME, // a floating point time (these are fixed up automatically too!)
	FIELD_MODELNAME, // Engine string that is a model name (needs precache)
	FIELD_SOUNDNAME, // Engine string that is a sound name (needs precache)
	FIELD_TYPECOUNT, // MUST BE LAST
	} FIELDTYPE;