Fix simpleDuration, modifiedDuration and convexity with Act/Act(ISMA)

http://sourceforge.net/p/quantlib/bugs/162/

This commit fixes simpleduration, duration and convexity with
Act/Act(ISMA)
Changed name of ignored file.
Merge pull request #28 from Nick Glass.

Fixed yield-based duration calculations for some day counters.
Add new Act/365 NL Daycounter

Add Act/365 (NL) Daycounter.
This is used for Japanese Government Bonds
Renamed new day counter to more Actual365NoLeap.

This makes the name more explicit.
Commit updated header.
Export new day counter to SWIG.
Export new day counter to QuantLibAddin.
Merge pull request #27 from Nick Glass.

New Actual/365 (No Leap) day counter.
fixed unsigned int conversion (thanks to Peter Caspers)