Exposed forwardRate function.
Update datatype to float in SimpleQuote + unit test.
Deprecate float in favor of double.
Unit test for zero_rate and forward_rate.
Make bootstrap method return reference to term structure.
Merge pull request #54 from enthought/fix-float-datatypes

Replace float by double in Cython code.
Raise NotImplementedError on calling {zero, forward}_rate when term structure is relinkable.
Fixed line breaks and indentation.
Expanded Market test case.
Fixed variable inconsistency in Market.
Get shared pointer to linked term structure for {zero, forward}_rate.
Merge pull request #53 from enthought/enh-expose-forward-rate

Expose forward_rate function on YieldTermStructure.
Merge branch 'master' into enh-bond-helpers

Conflicts:
	quantlib/termstructures/yields/yield_term_structure.pyx
Whitespace cleanup.
Unit test for bond helper.
Deal with issue_date being None by default.