Make test_case_registration a default feature

Cargo.toml

@@ -36,9 +36,11 @@ members = [
 ]
 
 [features]
-# Use `#[test_case]`-based test registration (only works on nightly when `custom_test_frameworks` feature is enabled).
-# Without that feature turned on, the default test registration method is to use `ctor` crate to create a global list
-# of all tests.
+
+# Use `#[test_case]`-based test registration. If this is disabled, datatest will use the `ctor` crate to create a
+# global list of all tests.
+#
+# Enabled by default, only takes effect on nightly and only works when custom_test_frameworks feature is enabled.
 test_case_registration = []
 
 # Use very, very, very sketchy way of intercepting a test runner on a stable Rust. Without that feature, there are two
@@ -49,7 +51,7 @@ test_case_registration = []
 unsafe_test_runner = ["region"]
 
 # Make this crate useable on stable Rust channel. Uses forbidden technique to allow usage of this crate on a stable
-# Rust compiler. This, however, does not bring any guarantees above "nighly" -- this crate can break at any time.
+# Rust compiler. This, however, does not bring any guarantees above "nightly" -- this crate can break at any time.
 subvert_stable_guarantees = []
 
-default = []
+default = ["test_case_registration"]