Isoltets SMTChecker option and BMC specific tests

test/libsolidity/smtCheckerTests/bmc_coverage/assert.sol

@@ -0,0 +1,26 @@
+pragma experimental SMTChecker;
+contract C {
+	function f(uint x) public pure {
+		assert(x > 0);
+	}
+	function g(uint x) public pure {
+		require(x >= 0);
+	}
+	function h(uint x) public pure {
+		require(x == 2);
+		require(x != 2);
+	}
+	function i(uint x) public pure {
+		if (false) {
+			if (x != 2) {
+			}
+		}
+	}
+}
+// ====
+// SMTEngine: bmc
+// ----
+// Warning 4661: (81-94): BMC: Assertion violation happens here.
+// Warning 6838: (143-149): BMC: Condition is always true.
+// Warning 6838: (218-224): BMC: Condition is always false.
+// Warning 2512: (286-292): BMC: Condition unreachable.