C++ Library, fix and renaming of python functions, large python documentation cleanup

C++ Library

• Added the C++ library for homer_map_manager, all POI and map functions are done and ready to be used.
• ROI functions and load_floor() still need to be implemented.
• I did not add any angle computing functions to the C++ Lib, as it would make sense to remove those from homer_map_manager completely in the future.

Python Interface

• fixed modify_POI() to not require x and y to be passed and to not reset any POI values to their defaults. All parameters are now completely optional so that any subset of POI values can be changed independently.
• renamed the absurd name point_inside_ROIs() to get_ROIs_including_point() because it returns a list of ROIs
• renamed is_inside_ROI() to is_point_inside_ROI() because it only works with PointStamped()
• renamed add_POI_at_location() to add_POI_at_current_location() to make it clear that the current robot pose is used
• changed the diary-entry style function documentation to be shorter, without all the fluff and hopefully more precise