refactor: move impl into .cpp + fix include paths

src/webutil/Alist.cpp

@@ -0,0 +1,28 @@
+/* @file Alist.cpp */
+
+#include "Alist.hpp"
+
+namespace xo {
+    namespace web {
+        /* lookup association by name */
+        std::string_view
+        Alist::lookup(std::string n) const {
+            for (auto const & ix : this->assoc_v_) {
+                if (ix.first == n) {
+                    return ix.second;
+                }
+            }
+
+            return "";
+        } /*lookup*/
+
+        void
+        Alist::push_back(std::string n, std::string v) {
+            this->assoc_v_.push_back(std::make_pair(std::move(n), std::move(v)));
+        }
+    } /*namespace web*/
+} /*namespace xo*/
+
+
+
+/* end Alist.cpp */