Add new test-suite artifacts to .gitignore.

Newer versions of either boost or autotools started redirecting
test output to log files.
More ignored artifacts.
Merge pull request #43.

Allow negative forwards in Black formula as long as forward +
displacement is not negative.
Merge pull request #47.
Merge branch 'vendor'
remove the floor of atm, let the swaption helper handle this (the atm level computed here was wrong)
fix handling of gearings on second leg