Frees all memory occupied by placeholders generated with
As placeholders are cached and re-used, typically only a small amount of memory is occupied when using pH. However, if a large number of unique placeholders are no longer needed, it's a good idea to run this script when switching rooms or destroying the object which formerly used them.
Note that running this function will break any variables referencing placeholders. On the other hand, running
ph_create in sprite functions directly will simply regenerate sprites when they are needed, and
ph_free will appear to have no effect. As such, in both cases it is important only to run
ph_free when placeholders will no longer be referenced.