Support for float type

[doku]

Support for float or double type for matching. Columns with decimal numbers can't be used for matching right now. It would be useful if these numbers can be used to match within a few +- percentage.

[sonalgoyal]

@doku are you able to share some data which we can use for testing this?

[mliscombe]

Relevant data here:
https://github.com/anhaidgroup/deepmatcher/blob/master/Datasets.md
http://pages.cs.wisc.edu/~anhai/data1/deepmatcher_data/Structured.zip

[sonalgoyal]

Thanks 🙏🏽 @mliscombe

[navinrathore]

With the above data, we have confirmed that support of float/double and integer data is already present in the Zingg.
However, we have found a bug that would restrict working end-to-end with such data.
We'll fix the same under this issue.

[navinrathore]

The "z_source" column should be added at the end of the record for consistency. The alignDupes() function requires desired change.
The alignLinked() may also require similar change.
The other place of same interest is getFieldDefColumns(). All functions are from DSUtil.java.