add rebates
move rebated exercise class to experimental/exercise
Fix delta and Gamma in Ju quadratic engine.

Thanks to Fabien Le Floc'h for the fix.
Increased time steps in convertible-bond test.
Replace explicit allocation with make_shared.
Try to avoid intermittent test failure.

Instead of increasing the tolerance, I tried increasing the number of
grid point in the tree to get a more accurate result.
reorganized markov model code,
added new instruments and engines,
added one factor gsr model,
reformatting
Merge branch 'fix20131026' into revampmarkov

Conflicts:
	QuantLib/ql/experimental/Makefile.am
fixed startDate > referenceDate (-> throw exception)
Move leftover inclusions to where they are needed.
Revert changes to date() method.

The check would be redundant in loops. Instead, I added a dateAt()
method that checks the index (like vector::at).
Merge pull request #49.
patch for QL-SWIG and Ruby 1.9 (cf http://bugs.debian.org/733105)
further fixes to setup.rb for Ruby 1.9
reset to 1.4
Move inclusions to cpp file.
Renamed data member for consistency.

Unlike "indices", "indexes" was already used in other places.
Merge pull request #63.
Added missing virtual destructors.
Update links to videos.