Fix Wasm support (#64)

* Fix dependencies

* Replace rug with num-bigint

Cargo.toml

@@ -23,7 +23,7 @@ rand_chacha = "0.3"
 itertools = "0.9.0"
 subtle = "2.4"
 pasta_curves = "0.3.1"
-neptune = "6.1"
+neptune = { version = "6.1", default-features = false }
 generic-array = "0.14.4"
 bellperson-nonnative = { version = "0.3.0", default-features = false, features = ["wasm"] }
 num-bigint = { version = "0.4", features = ["serde", "rand"] }
@@ -33,5 +33,5 @@ bincode = "1.2.1"
 flate2 = "1.0"
 
 [features]
-default = [ "bellperson/default", "bellperson-nonnative/default" ]
-wasm = [ "bellperson/wasm", "bellperson-nonnative/wasm" ]
+default = [ "bellperson/default", "bellperson-nonnative/default", "neptune/default" ]
+wasm = [ "bellperson/wasm", "bellperson-nonnative/wasm", "neptune/wasm" ]