Revert "Only add wstring versions of toString if wchar_t has been defined. This fixes some issues on embedded platforms where wstring isn't available."
This will be done with a simple #ifdef instead.
This reverts commit 6498a5112cf02cddeb0b300d9ad3620159c9931f.
Add the possibility to define CATCH_CONFIG_NO_WSTRING to disable wstring support on platforms where it's not supported (AVR32, for example).