allow multicoil dataset coil map estim + fastmri multicoil + cmrxrecon singlecoil

[Andrewwango]

closes #23

• support multicoil fastmri
• estimate automatically coil maps
• save to fastmri_multicoil dir

• add cmrxrecon (supports both singlecoil and multicoil)

[melanie-dohmen-bayer]

Hi @Andrewwango @MatthiasLen,

I noticed, that the multi-coil data was not compatible with the oasis model, I tried to add the missing adaptions. The results look ok, if no additional distortion is applied:

for variable undersampling, the results are also fine, I would say:

but for the equidistant undersampling, the model fails:

Is this possible/expected?

@Andrewwango could you review my changes on your branch?

Best regards,
Melanie

[melanie-dohmen-bayer]

@Andrewwango:
Please check my adaption for using the oasis fft path, apart from that, thanks a lot for your contribution!