Merge branch 'irnss' of

src/changes/changes.xml

src/main/java/org/orekit/gnss/IRNSSAlmanac.java

...kit/propagation/analytical/gnss/IRNSSOrbitalElements.java

...g/orekit/propagation/analytical/gnss/IRNSSPropagator.java

src/main/java/org/orekit/time/AbsoluteDate.java

src/main/java/org/orekit/time/DateComponents.java

src/main/java/org/orekit/time/GNSSDate.java

...propagation/analytical/gnss/IRNSSOrbitalElementsTest.java

...ekit/propagation/analytical/gnss/IRNSSPropagatorTest.java

src/test/java/org/orekit/time/AbsoluteDateTest.java

src/test/java/org/orekit/time/GNSSDateTest.java