Follow-up to Global_Function updates (97687ca).
* Added format string to "F_InsertPlural" for added flexibility.
* Added more checks to "F_GetPlural" for better handling of multi-word arguments (e.g. items).
* Updated some more scripts with new functions.

Some misc. cleanup of constants in scripts.

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