refactor into cmake project, tweak api

example/path.cpp

@@ -0,0 +1,17 @@
+#include "tc/solver.h"
+#include "tc/groups.h"
+
+#include <ctime>
+#include <iostream>
+
+int main() {
+    auto cube = tc::group::B(3);
+    auto vars = tc::solve(cube, {});
+
+    for (int target = 1; target < vars.len; target++) {
+        auto &action = vars.path[target];
+        std::cout << action.coset << " " << action.gen << " " << target << std::endl;
+    }
+
+    return 0;
+}