Fixed compilation errors for projects with unicode settings enabled

[NotRequiem]

• Fixed string function returning nullptr instead of empty strings when handling failure
• Initialized core class variables to avoid ISO standard warnings
• Modified the usage of const_cast to _T

const struct map_key {
            LPCTSTR KeyPath;
            LPCTSTR ValueName;
        } ResourceRegistryKeys[ResourceRegistryKeysLength] = {
            {
                const_cast<LPTSTR>("Hardware\\ResourceMap\\System Resources\\Physical Memory"),
                const_cast<LPTSTR>(".Translated")
                _T("Hardware\\ResourceMap\\System Resources\\Physical Memory"),
                _T(".Translated")
            },
            {
                const_cast<LPTSTR>("Hardware\\ResourceMap\\System Resources\\Reserved"),
                const_cast<LPTSTR>(".Translated")
                _T("Hardware\\ResourceMap\\System Resources\\Reserved"),
                _T(".Translated")
            },
            {
                const_cast<LPTSTR>("Hardware\\ResourceMap\\System Resources\\Loader Reserved"),
                const_cast<LPTSTR>(".Raw")
                _T("Hardware\\ResourceMap\\System Resources\\Loader Reserved"),
                _T(".Raw")
            }
        };

• Made some lambda functions use const variables to improve performance
• Changed the unicode/ascii usage of certain Windows API calls