chemical treatment (ZECO_0000111) - make def species agnostic

[sjm41]

chemical treatment (ZECO_0000111)
Experimental condition in which the fish is treated with a chemical substance. This treatment could be administered by adding the chemical substance to the tank water, injections, or by consumption.

If this term is to be used by non-ZFIN groups within phenotype and disease model annotations at the Alliance, then the definition needs to become species agnostic. So it could be changed to something simple like "Experimental condition in which the organism is treated with a chemical substance."

Most child terms already look OK - just need to change last one:

chemical treatment by diet (ZECO_0000239)
Chemical treatment condition in which the chemical is introduced through the diet.

chemical treatment by environment (ZECO_0000238)
Chemical treatment condition in which the chemical is introduced through the environment. For zebrafish this is the tank water.

chemical treatment by gavage (ZECO_0000255)
Chemical treatment condition where the chemical is introduced to the organism by gavage.

chemical treatment by injection (ZECO_0000237)
Chemical treatment in which the chemical is injected into the zebrafish.
...change to:
Chemical treatment in which the chemical is injected into the organism.

Alternative approach would be to keep fish-specific terms/defs, and then introduce a bunch of more generic parents, but I don't think that's necessary (at least not for these examples).