macOS: Provide a sensible default for the file system case-sensitivity

Having a case-sensitive file system on macOS results in problems that make QC almost unusable.

Several file changes are no more correctly recognized [due to using wrong paths inside QFileSystemWatcher] as soon you're using defaults [default location for projects is /Users/loginname]

• adding files to the current project using a wizard
• file modifications from outside
• path/file removal from outside
• using VCS

All in all I'd say this makes not a good 'first impression' when trying out/evaluating QC the first time and being on a case-sensitive fs.. Not sure how many users are really affected by this (or whether it's just me?)

Suggestion: Either use a sensible default [case-sensitive as this will _always_ work] or decide whether to use case-sensitive / case-insensitive when setting up QC the first time.
Having more than 1 fs mounted on a UNIX based system is not unlikely - and having a separate disk - maybe with a case-sensitive fs - for development seems not impossible to me.

As I wasn't even aware of the fact, that the setting exists, I'd appreciate a warning somewhere stating that I'm on a case-sensitive fs although having case-insensitive set inside QC's settings.