v0.6.0

MRFingerprintingRecon v0.6.0

Diff since v0.5.5

Merged pull requests:

• Release 0.5.5 (#27) (@JakobAsslaender)
• GROG speedup (#28) (@JakobAsslaender)
• WIP: re-write GROG/Cartesian interface (#30) (@JakobAsslaender)
• Split fbp from coil maps (#31) (@SebastianFlassbeck)