Change internal repr. to 4×Integer from 2×Rational+Integer
Swap qi and qi' everywhere
Make things work on new QI repr. without conversions
Make some tests a bit nicer
Add test for qiToContinuedFraction/continuedFractionToQI
Implement proper Show and Read for QI
qiRecip: Fix comment
Add qiIsZero
qiRecip fails for certain inputs; raise error for now
INLINE all the things!