Merge pull request #9269 from Thalpy/FermiGrenades

Re-enables fermichem mechanics for grenades, nuances heat for general handling and enables SDGF/hatmium explosions.

code/modules/reagents/chemistry/holder.dm

@@ -496,7 +496,12 @@
 
 		//Standard reaction mechanics:
 			else
-				if (C.FermiChem == TRUE)//Just to make sure
+				if (C.FermiChem == TRUE)//Just to make sure, should only proc when grenades are combining.
+					if (chem_temp > C.ExplodeTemp) //To allow fermigrenades
+						var/datum/chemical_reaction/fermi/Ferm = selected_reaction
+						fermiIsReacting = FALSE
+						SSblackbox.record_feedback("tally", "fermi_chem", 1, ("[Ferm] explosion"))
+						Ferm.FermiExplode(src, my_atom, volume = total_volume, temp = chem_temp, pH = pH)
 					return 0
 
 				for(var/B in cached_required_reagents) //