Remove allow_growth field in SpeciesType struct.

[chaukap]

Species[sp]->allow_growth is a seed dispersal specific variable that is unnecessary in the current implementation.

The documentation, a hold over from DLM, reads

Seed dispersal only- whether to allow growth for the current year.

Which makes no sense given our implementation of seed dispersal.

It is set to TRUE in _species_init then never modified again. Therefore, it it useless and can be removed.

[kpalmqui]

@chaukap thanks! looks like we also need to remove the mention of allow_growth in the DLM_change_log.txt file.

[chaukap]

@kpalmqui My vote is to delete the file DLM_change_log.txt most of the changes that are mentioned in the file have been undone, not just allow_growth, plus I don't think reading this file would help any future programmers understand the program.

[kpalmqui]

@chaukap I would like to briefly review it before we delete it. Thanks!

[chaukap]

After discussion we have decided to remove DLM_change_log.txt. I opened issue #450 to address the removal.