Turn on MathJax for Doxygen
More notes about solving Problem 9, not yet working
Add numbers::divisors and numbers::divisorsUnsorted with tests
Remove unneeded header from Divisor.h
Add number::isqrt with very basic implementation and start of tests
Add more tests for number::isqrt and mpz_class specialization
Correct specialization of number::isqrt. Still need to figure out a way for mpz_class expression templates to specialize correctly
Fix number::isqrt as much as it can. Will just have to explicitly cast when using mpz_class