Build panel and reworking Open paths, not compiling

src/basic/basic_string.cpp

@@ -84,6 +84,13 @@ API String GetPrefix(String a, int64_t len) {
     return result;
 }
 
+API char At(String a, int64_t idx) {
+    if (idx < a.len) {
+        return a.data[idx];
+    }
+    return 0;
+}
+
 API String GetSlice(String arr, int64_t first_index, int64_t one_past_last_index) {
     // Negative indexes work in python style, they return you the index counting from end of list
     if (one_past_last_index == SLICE_LAST) one_past_last_index = arr.len;