resolc crate (#328)

- Factor the YUL crate out of `revive-solidity`.
- `revive-solidity` is in reality not a Solidity implementation but the
revive solidity compiler driver (`resolc`). By renaming we not only get
this straight but also a binary with the same name as the crate which
should be less confusing.

---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

crates/resolc/src/tests/remappings.rs

@@ -0,0 +1,50 @@
+//! The Solidity compiler unit tests for remappings.
+
+#![cfg(test)]
+
+use std::collections::BTreeMap;
+use std::collections::BTreeSet;
+
+pub const CALLEE_TEST_SOURCE: &str = r#"
+// SPDX-License-Identifier: MIT
+
+pragma solidity >=0.4.16;
+
+contract Callable {
+    function f(uint a) public pure returns(uint) {
+        return a * 2;
+    }
+}
+"#;
+
+pub const CALLER_TEST_SOURCE: &str = r#"
+// SPDX-License-Identifier: MIT
+
+pragma solidity >=0.4.16;
+
+import "libraries/default/callable.sol";
+
+contract Main {
+    function main(Callable callable) public returns(uint) {
+        return callable.f(5);
+    }
+}
+"#;
+
+#[test]
+fn default() {
+    let mut sources = BTreeMap::new();
+    sources.insert("./test.sol".to_owned(), CALLER_TEST_SOURCE.to_owned());
+    sources.insert("./callable.sol".to_owned(), CALLEE_TEST_SOURCE.to_owned());
+
+    let mut remappings = BTreeSet::new();
+    remappings.insert("libraries/default/=./".to_owned());
+
+    super::build_solidity(
+        sources,
+        BTreeMap::new(),
+        Some(remappings),
+        revive_llvm_context::OptimizerSettings::cycles(),
+    )
+    .expect("Test failure");
+}