imwrite or imread loses channel dimension

[data2code]

In the example below, I save a single channel 3D image ZCYX with imwrite. imread() returns a 3d array, the single channel is squeezed away.
This makes it difficult to know if the first axis is Z or C.

Thank you!

>>> img=(np.random.rand(10,1,100,100)*255).astype(np.uint8)
>>> img.shape
(10, 1, 100, 100)
>>> tifffile.imwrite("test.tiff", img, compression='zlib', metadata={'axes': "ZCYX"}, imagej=True)
>>> tifffile.imread("test.tiff").shape
(10, 100, 100)

For more than one channel, it's not a problem. Maybe there is a way for me to disable sequeeze?

>>> img=(np.random.rand(10,2,100,100)*255).astype(np.uint8)
>>> tifffile.imwrite("test.tiff", img, compression='zlib', metadata={'axes': "ZCYX"}, imagej=True)
>>> tifffile.imread("test.tiff").shape
(10, 2, 100, 100)

[cgohlke]

Try squeeze=False, which returns the array in TZCYXS order (most commonly for ImageJ):

>>> tifffile.imread("test.tiff", squeeze=False).shape
(1, 10, 1, 100, 100, 1)

[cgohlke]

See also #19 and #66.