littletable 2.3. 5DD1 1

Added Table.batched, similar to itertools.batched added in Python 3.13. Returns a generator that yields tables sliced into n-sized batches:
```
for mini_table in tbl.batched(10):
    ... work with table containing only 10 entries ...
```
Extended arguments support in Table.splitby to accept named arguments that define the predicate splitting function in terms of the specific value of one or more row attributes:
```
qa_data, production_assembly_data = data.splitby(
  lambda rec: rec.env == "prod" and rec.dept == "assembly"
)
```
can be written as:
```
qa_data, production_data = data.splitby(env="prod", dept="assembly")
```
Added using argument to Table.create_search_index to simplify creation of a search index attribute by using multiple existing attributes. See this example from the explore_unicode.py example:
```
unicode.create_search_index(
    "name_words",
    using=["name", "unicode_1_name", "iso10646_comment"],
)
```
The example creates a new field name_words by combining the attributes name, unicode_1_name, and iso10646_comment, and then builds a search index using this new field.

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