Reduce 3+ second json load to ~2 seconds by eliminating ~240000 fseeks

Still slow, only hippopotamus slow instead of gaint ground sloth megafauna slow
**before**
14:40:1.597 INFO : game.cpp:96: load_json_dir
14:40:3.612 INFO : game.cpp:98: init_npctalk
14:59:58.113 INFO : game.cpp:96: load_json_dir
15:0:1.393 INFO : game.cpp:98: init_npctalk
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 51.92    0.008892           0    228582           read
 24.01    0.004113           0    242837           _llseek
 23.36    0.004001        4001         1           waitpid

 **after**
 
15:3:28.345 INFO : game.cpp:96: load_json_dir
15:3:30.383 INFO : game.cpp:98: init_npctalk
15:5:20.989 INFO : game.cpp:96: load_json_dir
15:5:22.998 INFO : game.cpp:98: init_npctalk

% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 97.99    0.004000        4000         1           waitpid
  2.01    0.000082           0      5886           getcwd
  0.00    0.000000           0       144           read