Minor refactor, added optional recursive dups for ast, ...

- Added support for anonymous structs.
- Gave Token_Fmt::token_map its own static memory.
- Minor natvis fix for CodeBody
- Renamed ESpecifier::Static_Member to just Static (acts as a general use case) specifier option
- Setup the lex token array with a configurable arena allocator.

Two major things left before V0.3-4:
- Attribute and Module parisng support with base case test
- AST serializtaion strings get a dedicated slag allocator.

scripts/gencpp.natvis

@@ -365,8 +365,8 @@
 		<DisplayString Condition="ast != nullptr">{ast->Name} {ast->Type}</DisplayString>
 		<Expand>
 			<Item Name="Parent">ast->Parent</Item>
-			<Item Name="Prev">ast->Front</Item>
-			<Item Name="Next">ast->Back</Item>
+			<Item Name="Front">ast->Front</Item>
+			<Item Name="Back">ast->Back</Item>
 			<Item Name="NumEntries">ast->NumEntries</Item>
 		</Expand>
 	</Type>