initial mostly-untested fixed-size-bignum implementation
add compile-tests for bignum
Merge branch 'master' of https://github.com/elidupree/Lasercake
bignum: add some tests, fix some bugs
more bignum tweaks
bignum & naming cleanness (lossless_multiply replaces

'width_doubling_multiply' and 'multiply_to_fit' names)
more bignum work
i64sqrt->isqrt and concomitant changes
test that bigint works in physical_quantity.

It doesn't work in bounds_checked_int yet; bounds_checked_int
is going to need a bit of refactoring.
Merge branch 'master' of https://github.com/elidupree/Lasercake
fix compile (for me at least) of grand_structure with GMP mpz
Fixed very many bugs. It now runs again.