targetSymbol in Eval::ImportCoin() must be checked for non empty

[dimxy]

targetSymbol field in the import transaction is compared to various values to determine the import type. One of the cases is the check against the ASSETCHAINS_SELFIMPORT chain var and treated as a gateway import tx. If both targetSymbol and ASSETCHAINS_SELFIMPORT are empty the code flow enters gateway import statements what it should not do.
Both ASSETCHAINS_SELFIMPORT targetSymbol should be checked as non-empty in Eval::ImportCoin() before allowing to go further in the import tx validation.
(should ASSETCHAINS_SELFIMPORT be checked to a specific value like "GATEWAY"?)

[dimxy]

fixed in the tokel branch.
thanks Decker for finding this

[dimxy]

not yet fixed in dev

[dimxy]

fixed in PR #559