|Copy a file into another|
|This is like the file_copy function, but with some goodies to track the copy process.|
|void fail (const char *src, const char *dst, const char *details)|
|void progress (const char *src, const char *dst, size_t size, size_t sofar, bool &end)|
Return -1 if any error
The copy is ended and you are informed about it. The default behavior is to report the error with tlmp_error()
It is generally used to present a progress bar. The default is to do nothing.