chg: estimate term growth through shifting evaluation point in ezgcd
fix: stupid bug in ezgcd
chg: faster gcd computation in EZGCD in corner cases
chg: switch to sparse modular GCD in some cases
fix: bad condition
chg: tuning parameter in sparseGCDFp
chg: switch to dense modular GCD
chg: updated test results
Merge pull request #260 from mmklee/factory_gcd

Factory gcd