Reduce 3+ second json load to ~2 seconds by eliminating ~240000 fseeks. Also, close files after read.

Magically transmutates insane amount of fseeks into insane amount of stringbuffer seeks.
Still slow, only hippopotamus slow instead of gaint ground sloth megafauna slow
**before**
14:40:0.597 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