Support nested macro definitions (#7004)

* First commit

* Switched to \end <name> instead of all those repeated backslashes

Thanks @kookma. See https://github.com/Jermolene/TiddlyWiki5/pull/7004#issuecomment-1286429236

* Docs update

editions/test/tiddlers/tests/data/macros/NestedMacros.tid

@@ -0,0 +1,36 @@
+title: Macros/NestedMacros
+description: Nested Macros
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+
+\define outer()
+\whitespace trim
+
+\define middle()
+\whitespace trim
+
+\define inner()
+\whitespace trim
+
+Jaguar
+
+\end inner
+
+<<inner>>
+
+\end middle
+
+<<middle>>
+
+\end outer
+
+<<outer>>
+
++
+title: ExpectedResult
+
+<p>Jaguar</p>