some cleanup to cashflow.pyx
simple calendar registry
refactored Calendar.from_name into the usage of a CalendarRegistry
exposing calendar_from_name and allowing registration of new Calendars
without compilation
uses tabulate in CalendarRegistry, fixes to help str for Legs
adding missing test file
Merge branch 'master' into build_ql_1.4
add tabulate to the travis dependencies
refactored the CalendarRegistry into a more 'generic' ObjectRegistry
add info about windows build fixed
Updated build instructions from source on Linux
Merge pull request #72 from phenaff/docs

Updated build instructions from source on Linux
removing prettyprint from swap conventions
new currency_registry, moved all the currency related modules under
quantlib/currency/
removed term_structure_factory function (should be using the
PiecewiseYieldCurve constructor)
fixing tests to use the new currency_registry and no more
term_structure_factory
removed help method from Currency (should use docstring or the registry)
refactored help methods of Thirty360 and ActualActual in favour of using a
docstring
removed prettyprint module, replaced by tabulate
expose BusinessDayConvention in quantlib.time.api, refactor its help method in
a docstring
remove unused DataStore