Support for large images and recovery partition sizes over 2 GB

Patchset for a project that needed support for larger images.

- Fixes support for recovery partitions larger than 2 GB
- Fixes status reporting for images whose uncompressed size is larger than 4 GB
- Minor fixes 
  * make NOOBS compile with the desktop edition of Qt, so you can see compile errors in Qt creator. 
  * fixes a warning about a signed char being used where it should have been an unsigned char.
  * only moves the start of the recovery FAT partition when it is not MiB aligned already.