PhotoCraft portable mode

While this file sits next to photocraft.exe, PhotoCraft keeps its preferences, brush presets,
crash-recovery autosaves and startup state in the PhotoCraftData folder beside it, and writes
nothing to %APPDATA% or %LOCALAPPDATA%. Copy the whole folder to move PhotoCraft with its settings.

Delete this file to use the normal per-user folders instead: %APPDATA%\Photocraft for settings
and %LOCALAPPDATA%\Photocraft\Recovery for crash-recovery autosaves. If PhotoCraftData can't be
written (for example on a read-only drive), PhotoCraft says so and uses those folders instead.