Make "largestID" sum with "v" (int) rather than concatenate (str)
Tested by creating a simple geometry with one space, saving, then adding a second space and saving again. Opening the first file and re-adding the second space, and saving for a third time. Before the change, this process produced different internal IDs in the second and third save files. After this change the IDs were identical, as intended
Make "largestID" sum with "v" (int) rather than concatenate (str) Tested by creating a simple geometry with one space, saving, then adding a second space and saving again. Opening the first file and re-adding the second space, and saving for a third time. Before the change, this process produced different internal IDs in the second and third save files. After this change the IDs were identical, as intended