Add modules highlighting

Still debating whether modules should be highlighted as namespaces or as
function calls.

queries/highlights.scm

@@ -24,6 +24,13 @@
 
 ; Declarations {{{
 (identifier) @variable
+
+(module
+  type: (identifier) @module)
+
+(module
+  (property
+    field: (identifier) @variable.member))
 ; }}}
 
 ; vim: sw=2 foldmethod=marker

test/highlight/modules.bp

@@ -0,0 +1,21 @@
+foo {}
+// <- module
+
+foo ()
+// <- module
+
+foo {
+// <- module
+    field: 12,
+    // <- variable.member
+    another_field: 27,
+    // <- variable.member
+}
+
+foo (
+// <- module
+    field = 42,
+    // <- variable.member
+    done = false,
+    // <- variable.member
+)