Hashtable update

- use consistent type for key by introducing a new typedef
- use unsigned types for sizes
- name parameters in foreach function typedef

Action.c

@@ -100,7 +100,7 @@ static bool changePriority(MainPanel* panel, int delta) {
    return anyTagged;
 }
 
-static void addUserToVector(int key, void* userCast, void* panelCast) {
+static void addUserToVector(hkey_t key, void* userCast, void* panelCast) {
    const char* user = userCast;
    Panel* panel = panelCast;
    Panel_add(panel, (Object*) ListItem_new(user, key));