Expand test framework and test cases (#685)

* Fix comment

* Ekf wrapper for testing

Add utility function for accessing information in the ekf object

* Add step function for Gps sensor

* Add RangeFinder and Flow to simulated sensors

* Add first fusion logic tests

* Add units to function name

* Use EXPECT_TRUE

* Adding missing qualifiers

* Improve EXPECT_ calls

* Improve naming

test/CMakeLists.txt

@@ -41,6 +41,7 @@ set(SRCS
 	test_EKF_ringbuffer.cpp
 	test_EKF_imuSampling.cpp
 	test_AlphaFilter.cpp
+	test_EKF_fusionLogic.cpp
    )
 add_executable(ECL_GTESTS ${SRCS})