[1.7.0] Double backslashes in log

[SevenSpheres]

Describe the bug File paths in Celestia's log are displayed with double backslashes.

To Reproduce Steps to reproduce the behavior:

1. Type ~
2. See error

Expected behavior File paths should have single backslashes.

Screenshots

Desktop (please complete the following information):

• OS: Windows 10
• Frontend: Qt, Win
• Version: 1.7.0

Additional context Appears to be caused by #1139.

[ajtribick]

This matches the behaviour of the operator << from the C++17 filesystem library, which is specified to use std::quoted and therefore renders the double backslash escape sequence.

In C++17, a potential fix to make the log output nicer would be to use the u8string() method, unfortunately this is not forward-compatible with C++20 where this returns a std::u8string (made up of char8_t) instead of a std::string (made up of char) and therefore fails to compile. It would potentially be possible to use reinterpret_cast<const char*>(path_variable.u8string().c_str()), although as far as I'm aware using the result of this as an actual pointer to const char is undefined behaviour (but it probably works on all compilers).

[375gnu]

Those .string()/.u8string() are really anoying.

[SevenSpheres]

On the latest build, file paths in Celestia's log aren't displayed when a texture is successfully loaded. It's just "Creating ordinary texture..."

If a texture isn't found, the path is still displayed (with single backslashes); if a model is loaded the path is still displayed (with double backslashes).

[375gnu]

Verbosity of the message was raised from INFO to VERBOSE. There is still a lot to do to hided useless messages in default INFO mode.