gometalinter -> golangci-lint migration (#3933)

{,scripts/}Makefile:
- Remove gometalinter, install golangci-lint.
- Remove distinction between tools and devtools.
  Just tools is enough.
- test_lint -> lint
  Migrating away from underscore separated names.
- Remove unnecessary targets.
- Drop tendermint/lint. Incompatbile with golangci-lint
  and no longer necessary anyway.
- Fix misleading message in go-mod-cache.
- New ci-target to avoid download tools twice.
- Run tests with -mod=readonly.

Port tools/gometalinter.json to .golangci.yml
Update CircleCI config accordingly.

Closes: #3896

x/auth/client/cli/multisign.go

@@ -105,7 +105,9 @@ func makeMultiSignCmd(cdc *amino.Codec) func(cmd *cobra.Command, args []string)
 			if ok := stdSig.PubKey.VerifyBytes(sigBytes, stdSig.Signature); !ok {
 				return fmt.Errorf("couldn't verify signature")
 			}
-			multisigSig.AddSignatureFromPubKey(stdSig.Signature, stdSig.PubKey, multisigPub.PubKeys)
+			if err := multisigSig.AddSignatureFromPubKey(stdSig.Signature, stdSig.PubKey, multisigPub.PubKeys); err != nil {
+				return err
+			}
 		}
 
 		newStdSig := auth.StdSignature{Signature: cdc.MustMarshalBinaryBare(multisigSig), PubKey: multisigPub}

x/gov/client/cli/query.go

@@ -43,7 +43,7 @@ $ gaiacli query gov proposal 1
 
 			var proposal gov.Proposal
 			cdc.MustUnmarshalJSON(res, &proposal)
-			return cliCtx.PrintOutput(proposal)
+			return cliCtx.PrintOutput(proposal) // nolint:errcheck
 		},
 	}
 }
@@ -118,7 +118,7 @@ $ gaiacli query gov proposals --status (DepositPeriod|VotingPeriod|Passed|Reject
 				return fmt.Errorf("No matching proposals found")
 			}
 
-			return cliCtx.PrintOutput(matchingProposals)
+			return cliCtx.PrintOutput(matchingProposals) // nolint:errcheck
 		},
 	}
 
@@ -175,17 +175,21 @@ $ gaiacli query gov vote 1 cosmos1skjwj5whet0lpe65qaq4rpq03hjxlwd9nf39lk
 			}
 
 			var vote gov.Vote
-			cdc.UnmarshalJSON(res, &vote)
+			if err := cdc.UnmarshalJSON(res, &vote); err != nil {
+				return err
+			}
 
 			if vote.Empty() {
 				res, err = gcutils.QueryVoteByTxQuery(cdc, cliCtx, params)
 				if err != nil {
 					return err
 				}
-				cdc.UnmarshalJSON(res, &vote)
+				if err := cdc.UnmarshalJSON(res, &vote); err != nil {
+					return err
+				}
 			}
 
-			return cliCtx.PrintOutput(vote)
+			return cliCtx.PrintOutput(vote) //nolint:errcheck
 		},
 	}
 }

x/gov/client/rest/rest.go

@@ -346,7 +346,10 @@ func queryDepositHandlerFn(cdc *codec.Codec, cliCtx context.CLIContext) http.Han
 		}
 
 		var deposit gov.Deposit
-		cdc.UnmarshalJSON(res, &deposit)
+		if err := cdc.UnmarshalJSON(res, &deposit); err != nil {
+			rest.WriteErrorResponse(w, http.StatusBadRequest, err.Error())
+			return
+		}
 
 		// For an empty deposit, either the proposal does not exist or is inactive in
 		// which case the deposit would be removed from state and should be queried
@@ -420,7 +423,10 @@ func queryVoteHandlerFn(cdc *codec.Codec, cliCtx context.CLIContext) http.Handle
 		}
 
 		var vote gov.Vote
-		cdc.UnmarshalJSON(res, &vote)
+		if err := cdc.UnmarshalJSON(res, &vote); err != nil {
+			rest.WriteErrorResponse(w, http.StatusBadRequest, err.Error())
+			return
+		}
 
 		// For an empty vote, either the proposal does not exist or is inactive in
 		// which case the vote would be removed from state and should be queried for