Bm.integer-math

* All implementations going forward for integer_math module will use
just integer based algorithms. I can't really compete with C based
code from the Python standard library. The algorithms will then be
of use if ported to a platform without floating point arithmetic.
* added two new functions to the integer_math module
* iSqrt() finds the int square root of an int
* does same thing as math.isqrt()
* isSqr() return true if integer argument is a perfect square

* Forgot to update pyproject.toml dependencies
* dependencies = ["grscheller.circular-array >= 0.1.1, < 1.1"]

* now needs CircularArray v0.1.2
* integer_math comb uses new foldL method of CircularArray
* CircularArray was split out of grscheller.datastructures
* test suite written

* fixed some negative value edge cases
* lcm(0,0) now gives 0 instead of a divide by zero exception
* some authors leave lcm(0, 0) as undefined
* lcm(0, 0) = 0 does make sense
* since a*0 = 0 for all a >= 0
* 0 is the smallest non-negative integer a such that a*0 = 0
* most math theorems remain true for this case
* README.md improvements

* initial PyPI grscheller.boring-math release
* updated pyproject.toml to align with grscheller.datastructures

* working on pyproject.toml infrastructure for PyPI releases
* will use Flit as the packaging/publishing tool
* replaced bin/ scripts with `boring_math.integer_math_cli` entry-points