imageName
This is a global variable, likely for Hydra it should be hung off the VM interpreter local storage. 

**From**: Interpreter writeImageFileIO, and snapshot and writeImageFile (set mac file type)
**Why**: 
Storage for the image file name that is used by writeImageFileIO, has to be in file system representation
**Responsibility**:
This is a bit messy since on the iPhone and OSX the imagePath is stored both as a URI and as a character string. 
Has to be in platform encoding since it's used directly for platform IO routines

**MacIntosh**
//os-9/OSXCarbon//
char *getImageName(void) populates imageName via 
 CFStringGetCString (imageNameString, target, IMAGE_NAME_SIZE, encoding); via
 getImageNameWithEncoding(imageName,gCurrentVMEncoding);
where imageName is 
HFS+  imposes Unicode2.1 decomposed UTF-8 encoding on all path elements

//Cocoa://
See iPhone

**iPhone**
uses imageNamePutLength to populate imageName as a result of findImageViaBundleOrPreferences

**Unix**
imageName is populated at image read time, if a partial path it's made absolute.

**Windows**
imageName is used to read the image file, it's populated at startup time. This is the reverse of other platforms where 
a path is calculated to read the file, and later imageName is populated

**BUGS**
how big is unclear and platform dependent.