[PLAT-6692] Updating deprecation message

To point to correct classes to get the cash flows of an interest rate swap
[PLAT-6714] Added swap test for Fed Fund v Libor swap.
[PLAT-6714] Added more swap examples (basis swap). Added generator for OIS leg (ONCompounded).
[PLAT-6714] Added cubic spline interpolator for Fed Fund swap curves.
PLAT-6741 added 25 year to USD curve test data
[PLAT-6714] Added lege generator with coupon ON AA simplified. Refactor some of the generators for the swaps (generic legs).
[PLAT-6714] Changed tests results to fit with the new curve interpolation and data.
[PLAT-6714] Added swap ON Cmp v ON AA to the swap tests list. Corrected toDerivative in CouponONSpread to take the spread into account.
PLAT-6691 - Enable optional property placeholders

Fix case where optional is present
Simpler implementation using a null
Fix potential for interpolation to change wrong key
Change logging level to info

ToolContext elements are all optional
Update release notes
Bump version to 2.5.0-SNAPSHOT
[PLAT-6714] Added pv test with Fed Fund based curves.
[PLAT-6714] Added more end-to-end tests.
[PLAT-6728] Correct sign of initial notional and added relevant test.
Merge pull request #179 from OpenGamma/topic/plat-6728

[PLAT-6728] Correct sign of initial notional and added relevant test.
[PLAT-6714] Added XCcy generator. Added Xccy swap example in the swap tutorial.
Merge branch 'develop' into topic/plat-6714
[PLAT-6714] Added curve calibration of ON rate in XCcy settings.
[PLAT-6714] Clean files for comments and javadoc.