Fixed visit lookup issues on gcc 7 & 8 (#870). Thanks @medithe.

Fixed linkage errors on older gcc.

Prevented fmt/range.h from specializing fmt::basic_string_view (#865, #868). Thanks @hhggit (dual).

Improved error message when formatting unknown types (#872). Thanks @foonathan (Jonathan Müller),

Disabled templated user-defined literals when compiled under nvcc (#875). Thanks @CandyGumdrop (Candy Gumdrop),

Fixed format_to formatting to wmemory_buffer (#874).