Revert "Some refactoring"

This reverts commit 803c02293f20297a940c03d3386a1928cd882681.

Conflicts:
	include/sampgdk/core.h
Add a new callback to filter public calls

PLUGIN_EXPORT bool PLUGIN_CALL OnPublicCall(AMX *amx, const char *name,
                                            cell *params) {
  sampgdk_logprintf("Public called: %s", name);
  return true;
}
Rename sampgdk_callback_lookup to sampgdk_callback_find

For consistency with other APIs.
Add prototype and documentation for OnPublicCall
Remove float from the specifier table

double already covers float. This is like int assumes that short, char,
etc are possible too, so there's no point in listing them.