SCore:
- Refactored logic for checkamount placeholder
- Added checkvar as substitute for checkitem's placeholders (checkitem can't detect doubles and I'm not gonna submit a PR to checkitem)
- Made a custom argument extractor so it doesn't have complications when dealing with arg inputs that contains underscores

ExecutableItems:
Added placeholders for PLAYER_PICKUP_ITEM

%item_type% : Returns Material value
%item_name% : Returns ItemStack display name
%item_amount% : Returns ItemStack amount
%item_cmdata% : Returns custom model data value
%item_cmdata_f_0% : Returns the first value of the floats custom model data array
%item_cmdata_s_0% : Returns the first value of the strings custom model data array

By Special70