feature: boundary window for cgrams #21
Description
It would be useful to optionally produce cgrams within a window of X characters "beyond" the character change boundary.
For example, the default behavior of pack2 cgrams would have a range value of 0. With a specified range of '1',this input:
abcd1234
... would produce:
abcd
abcd1
d1234
1234
... and a range of '2' would produce:
abcd
abcd1
abcd12
cd1234
d1234
1234
In other words, this would produce a focused subset of what would be generated by window/slider tools, or tools like cutb, still informed by character-change boundaries.