Get the name assigned to the ea by the debugger module
ea - linear address
how - one of the DEBNAME_ constants
string get_debug_name(long ea, long how);
#define DEBNAME_EXACT 0 // find a name at exactly the specified address
#define DEBNAME_LOWER 1 // find a name with the address >= the specified address
#define DEBNAME_UPPER 2 // find a name with the address > the specified address
#define DEBNAME_NICE 3 // find a name with the address <= the specified address