Fixed an error with the '+=' operator on string variables

When attempting to concatenate and assign to a previously empty string
with +=, it'd throw a memory manager error. Follow-up to 22d2718.

Signed-off-by: Haru <haru@dotalux.com>
Script Engine Update Phase 1

Dropping array limits, test phase.
Also Implements a under-development (u)int64 key support to the dbmaps.
Made Possible Thanks to Haruna!

Signed-off-by: shennetsind <ind@henn.et>
Script Engine Update Phase 2

Fixed constant '\'' support (e.g. Monster's_Feed now works), made possible thanks to Haruna!
Ducked some debug messages in set_reg
- Script Engine Update: Phase 2, New Universal Shop Format
-- 4 new script commands (documentation will follow after test phase is complete)
--- openshop()
--- sellitem(...)
--- stopselling(...)
--- setcurrency(...)
-- new shops are fully able to be controlled by 'script' npc types, a new 'trader' npc subtype is available however which functions just like a 'script' type with the exception that clicking on 'trader' npc types automatically launches the shop as opposed to running the script from the start (shops under a 'script' type must use openshop() instead)
-- The shops powered by this feature have 5 unique currency types which can be adjusted with setcurrency, each shop can have up to 2 concurrent currencies (official behavior for cashshop npc types), default currency is zeny and, again, can be modified with setcurrency, available types are:
--- ZENY, CHAR_VAR (charreg), ACC_VAR (accreg), INSTANCE_VAR (instance-sub-mapreg), ITEM (item id/name)
-- check npc/merchants/shops.txt for a glimpse of the new design (Made Possible Thanks to Yommy!)
-- Design by Yommy, jaBote, mkbu95, Gepard and Emistry.

Signed-off-by: shennetsind <ind@henn.et>
Corrected line endings and BOM issues with several files

- Ensured final end-of-line character in every file.
- Corrected cases of mixed line endings (mostly CR and CRLF within the
  same file.)
- Removed extra BOM  from some scripts, since it causes a parsing error.

Signed-off-by: Haru <haru@dotalux.com>
Standardized the format of some NPC parse error messages

- For better machine-parsing of such messages (i.e. in IDEs)

Signed-off-by: Haru <haru@dotalux.com>
Script syntax checker