Improved 'client_hash_check' config. (Hercules e4a1ca2)
- Added option to disable hash check by GM group_id (specify 'disabled' as hash for a certain group_id to let them log in with any client, even if 'client_hash_check' is enabled.
- Updated and reworded related documentation for the feature.

Improvements on script command 'axtoi'; added 'strtol'. (Hercules 1cf7c1e)
- Added script command 'strtol' (conforming to the ISO C90 function).
- Modified script command 'axtoi' to internally use 'strtol' instead of an unnecessary separate implementation.

Cleaned up many sections of script documentation, and modernized syntax in examples.
Added documentation for 'rentitem2' and 'makeitem2'. (follow-up 339c0a8)

Added 'true' (1) and 'false' (2) as script constants.

'freeloop' argument is now optional, and will only return the value of freeloop if no argument is given. (tid:92470)
http://rathena.org/board/topic/92470-freeloop-optional-argument/

Added a missing mapflag to custom 'devil_square' script. (bugreport:8611)
http://rathena.org/board/tracker/issue-8611-devil-square-bug/

Signed-off-by: Euphy <euphy.raliel@rathena.org>