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#### Brief description of what is fixed or changed

With Python's big boxed integers, using one "<<" and one "&" is faster than two multiplications and two "&"s. Also added stronger filters, letting only 0.425% of cases get to the integer_nthroot computation.

#### Other comments

Benchmarks:
```python
from timeit import timeit
R = range(2_000_000)
x = timeit(lambda: sum(my_is_square(x, False) for x in R), number=3)
y = timeit(lambda: sum(sympy_is_square(x, False) for x in R), number=3)
print(x) # 1.632436300162226
print(y) # 2.681206800043583
```

#### Release Notes

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  * Added a new solver for logarithmic equations.

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* ntheory
  * Improved the performance of the `is_square(n)` function.
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