Update Vala Bindings to reflect recent changes in afrodite's API.
In particular,
* ast.vala has been renamed to codedom.vala,
* afrodite_symbol_get_symbol_data_type has been renamed to *_get_data_type,
* afrodite_symbol_get_symbol_type has been renamed to *_get_member_type.
Parser/Afrodite.cs: Fix calls to afrodite_symbol_get_symbol_type.
Rename Afrodite.Symbol.DataType to .SymbolType to match the naming of Afrodite's API.
Fix API call in Afrodite.Symbol.ReturnType.
Fix NullReferenceException in Parser.ProjectInformation.GetTypesVisibleFrom.
Use CodeDOM rather than CodeDom in comments.
Fix typo.
Merge pull request #118 from severinh/master

Update Vala bindings in response to recent changes in afrodite's API (vtg 0.12.1)