fixed extrapolation problem for VC9
Merge remote-tracking branch 'upstream/master' into quantlib-merge
added MaddockInverseCumulativeNormal (proxy for the corresponding boost
implementation)
fixed compiler issue with clang++ 3.3 and boost-1.53 in
test-suite/convertiblebonds.cpp
test only if boost version supports InverseCumulativeNormalDistribution
changed pImpl_ implementation
removed extra class for spline extrapolation
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Merge pull request #46.

When available from Boost, add Maddock inverse-cumulative normal
distribution.
Also fix an extrapolation problem in a test (probably due to numerical
error in floating-point calculations).