Avatar archive load/save

Update modify and correct Avatar Archive processing
- Default save/load path to Data/AvatarArchive folder
- Re-work load and save commands
- correct saving and loading of archive files
- Save the supplied snapshot to an image in the default path (mainly
for WebUI)
SceneManager updates

- add --skip-terrain switch to 'load oar' command
- add default load/save path for oars (if not specified)
- Implement short form version of 'load oar'
- Add 'smarts' to 'save oar' command,