starter: Add prepare_explorer POC

Don't forget: This is only a POC for prepare Explorer!
apps: Added cygwin support
start: Added error checking to temp cmd file
start: Fixed " handling in parameters
start: Compacted working directory change
lib/SetEnv: Refactored environment variable calculation
lib/SetEnv: Workaround for drive letter change

Junctions don't support relative destination, therefore we have to recreate all environment links.
The final solution is Symlinks, because it supports relative destinations, but creation of it requires administrative right...
lib/SetEnv: Splitted ShortcutLikeLink creation to CreateLink and SetLinkLikeShortcut
start: Set custom Documents directory