Added pixel index to TimeDependentLOS.

src/main/java/org/orekit/rugged/linesensor/LineSensor.java

src/main/java/org/orekit/rugged/los/FixedRotation.java

src/main/java/org/orekit/rugged/los/LOSBuilder.java

src/main/java/org/orekit/rugged/los/LOSTransform.java

src/main/java/org/orekit/rugged/los/TimeDependentLOS.java

...va/org/orekit/rugged/los/TimeIndependentLOSTransform.java

src/test/java/org/orekit/rugged/api/RuggedBuilderTest.java

src/test/java/org/orekit/rugged/api/RuggedTest.java