Add MenuNode function that returns referenced items

MenuNode.referenced() returns all symbols (and choices, for choice
symbols) referenced in the properties (prompt, defaults, selects,
ranges, etc.) and property conditions of the menu node.

Handy e.g. when generating cross-references.

1 files changed, 43 insertions, 0 deletions

diff --git a/tests/Kreferenced b/tests/Kreferenced
new file mode 100644
index 0000000..8dda5a2
--- /dev/null
+++ b/tests/Kreferenced
@@ -0,0 +1,43 @@
+config NO_REFS
+    bool
+
+config JUST_DEPENDS_ON_REFS
+    bool
+    depends on A && B
+
+if A
+
+menu "menu"
+    depends on B
+    visible if C
+    visible if D
+
+config LOTS_OF_REFS
+    bool "lots" if C || D
+    default E || F if G || H
+    default I || J if K || L
+    select M if N || O
+    select P if Q || R
+    imply S if T || U
+    imply V if W || X
+    depends on Y || Z
+
+endmenu
+
+endif
+
+config INT_REFS
+    int "int"
+    range A B if C && D
+    range E F if G && H
+
+choice CHOICE
+    bool "choice"
+
+config CHOICE_REF
+    bool "choice ref"
+
+endchoice
+
+comment "comment"
+    depends on A || B