Move bignum under the "experimental" feature flag

Previously it was the "bignum" feature flag

Author: axic

Cargo.toml

@@ -14,4 +14,4 @@ wee_alloc = "0.4.4"
 default = [ "std" ]
 std = []
 debug = []
-bignum = []
+experimental = []

circle.yml

@@ -30,3 +30,7 @@ jobs:
              cargo build --release --no-default-features
              cargo build --release --features debug
              cargo build --release --no-default-features --features debug
+             cargo build --release --features experimental
+             cargo build --release --no-default-features --features experimental
+             cargo build --release --features experimental,debug
+             cargo build --release --no-default-features --features experimental,debug

src/lib.rs

@@ -31,7 +31,7 @@ mod utils;
 #[cfg(feature = "debug")]
 pub mod debug;
 
-#[cfg(feature = "bignum")]
+#[cfg(feature = "experimental")]
 pub mod bignum;
 
 #[cfg(not(feature = "std"))]