Ensure consistent extra columns in SolutionArray

[ischoegl]

Changes proposed in this pull request

• Fix bugs in beta release of 2.5.0b1
• Ensure that dimensions of extra columns are consistent
• Enable multi-dimensional extra 'columns' (e.g. 2D arrays similar to what already exists for other SolutionArray attributes)
• Like the existing code, this PR takes advantage of NumPy for on-the-fly adjustments of data types.

If applicable, fill in the issue number this pull request is fixing

Fixes #895, fixes #930

Illustration

In [2]: gas = ct.Solution("air.yaml")
   ...: states = ct.SolutionArray(gas, 3, extra={"prop": [5, 6, 7]})
   ...: states.append(TPX=(1100, 3e5, "AR:1.0"), prop=[1, 2, 3]) # <--- Fix #895
   ...: 
---------------------------------------------------------------------------
[...]
ValueError: Encountered incompatible value '[1, 2, 3]' for extra column 'prop'.

In [3]: states.prop = ‘spam’ # <--- overwrite individual entries / Fix #930
   ...: states.prop
   ...: 
Out[3]: array([‘spam’, ‘spam’, ‘spam’], dtype=‘<U4’)

In [4]: states.prop = np.ones((3,4)) # <--- enable multi-dimensional extra 'columns'
   ...: states.prop
   ...: 
Out[4]: 
array([[1., 1., 1., 1.],
       [1., 1., 1., 1.],
       [1., 1., 1., 1.]])

In [5]: states.prop = [1, 2, 3, 4] # <--- ensure that dimensions are consistent
---------------------------------------------------------------------------
[...]
ValueError: Incompatible shapes for extra column 'prop': cannot assign value with shape (4,) to SolutionArray with shape (3,)

Checklist

• There is a clear use-case for this code change
• The commit message has a short title & references relevant issues
• Build passes (scons build & scons test) and unit tests address code coverage
• The pull request is ready for review

[ischoegl]

@speth / @bryanwweber ... I cannot request a review, but I’d appreciate if those fixes could make it into 2.5.

[ischoegl]

[minor edits are taken care of]

[speth]

I think these are useful improvements to eliminate some confusing behavior in the SolutionArray class. Just noticed a couple of things to fix up further.

[ischoegl]

@speth ... thanks for the review. I believe it's all addressed.

As for the other PR's, I can rebase once #946 is merged.

[speth]

Looks good, thanks.