Merge PR #4435: Simulation: Params from File

* Move distr params to simulation param generator

* Cleanup sim params output

* Print params when possible instead of entire genesis struct

* Update module param simulator keys

* Rename module params simulator keys

* Add/fix missing module params and implement SimParams

* UPdate sim test to accept params file

* Allow weights to be provided from file

* Create doc.go

* Remove TODO

* Implement MustMarshalJSONIndent

* Use mustMarshalJSONIndent for non-codec

* Remove TODO

* Fix doc.go

* Update points

* Update simapp/doc.go

Co-Authored-By: Alessio Treglia <quadrispro@ubuntu.com>

* Update simapp/doc.go

Co-Authored-By: Alessio Treglia <quadrispro@ubuntu.com>

* Cleanup appStateFn

* Use constants for simulation parameter keys

* Update msgs.go

* minor formatting

codec/codec.go

@@ -3,6 +3,7 @@ package codec
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 
 	amino "github.com/tendermint/go-amino"
 	cryptoAmino "github.com/tendermint/tendermint/crypto/encoding/amino"
@@ -35,6 +36,16 @@ func MarshalJSONIndent(cdc *Codec, obj interface{}) ([]byte, error) {
 	return out.Bytes(), nil
 }
 
+// MustMarshalJSONIndent executes MarshalJSONIndent except it panics upon failure.
+func MustMarshalJSONIndent(cdc *Codec, obj interface{}) []byte {
+	bz, err := MarshalJSONIndent(cdc, obj)
+	if err != nil {
+		panic(fmt.Sprintf("failed to marshal JSON: %s", err))
+	}
+
+	return bz
+}
+
 //__________________________________________________________________
 
 // generic sealed codec to be used throughout sdk