Misc minor fixes, round two

- Remove some of the paranoid fixes for the archive manager panel crash that don't seem to be necessary.
- Write crash logs to the user data directory; the app directory may not be writable, e.g. on my system it's `/usr/bin`!
- Fix a wx warning caused by trying to get a property's value before checking whether it's unspecified.
- Fix various uses of `%d` in log message formatting when the argument is `unsigned` or `size_t`—these produce warning dialogs in debug builds and I'm sick of them  :)
- Creating a new map in a directory didn't work.
- On `directory_added`, an archive panel would slightly incorrectly try to show its path controls.