Storage/testcase: Increment error count
Storage/testcase/tstVDSnap: Don't return immediately when something fails but cleanup first
Storage/testcase/tstVDSnap: Delete leftover images from a previous run
header (C) fixes
*,IPRT: Redid the ring-3 init to always convert the arguments to UTF-8.
VD: Interface cleanup. Merge the two involved structures (generic interface descriptor and callback table) into one, remove the duplicated interface wrappers in the backends and move the interface definitions into separate headers separating public and private interfaces.
VD: Move the generic virtual disk framework + backends to src/VBox/Storage and rename the files to get rid of the HDD part because it supports floppy and DVD images too