Release v0.6.60: allow apostrophes in custom corrections

src/core.h

@@ -19,6 +19,7 @@ struct Layout
     bool hasLetter(wchar_t ch) const;
 };
 bool letter(wchar_t ch);
+bool validAutoCorrection(const std::wstring &text, const std::wstring &alphabet);
 std::wstring lower(std::wstring text);
 std::wstring upper(std::wstring text);
 std::wstring convert(const std::wstring &, const Layout &, const Layout &, bool force = false);