Fixes compilation errors after the RTCM package addition in the PVT
block. It also adds a series of class members documentation in the code
using the Doxygen standard while fixing code style errors
Adding code for navigation message computation for GLONASS GNAV code.
Continues to fix the almanac position computation and fixes bugs in code
due to compilation errors, coding style and Doxygen documentation
Generates code for GLONASS GNAV Ephemeris, Almanac and UTC Model with
their respective decoding position indexes for string decoding and
message parsing. Starts developing of satellite position computation
based on its ephemeris and almanac information
Carles Fernandez