This refactors the object_h struct to store objects as indexes rather than pointers. This is a prerequisite for making the collection of objects dynamic in the future. See also #6100.
Follow-up to #5800 and #5829.
This was previously used for allowing scripts to set arbitrary values on
scripting objects. However, it was used by only a few scripting
functions and, as far as I know, no script uses this features.
This removes that feature which simplifies the code ade_index_handler
of.
This also simplifies the code that handles the userdata for libraries
provided by FSO.
This maintains the type information which can be used for enforce
const-correctness and also for implementing more advanced ways of
handling the type information.
Since atoi return 0 on error the code tries to access the waypoint list
with index -1 which causes an assert in the lookup code. This fixes that
by using the error detection capabilities of strtol.