Yellow belt modelling

Modelling of 3.10.2.1 to 3.10.2.6.
This involved the creation of a set of functions and procedures to create and handle emergency stops, along with a slight modification to their storage and changes to anything currently referencing them.

New rules were added to the HandleEuroradioMessage procedure to handle emergency stop messages.

Added pre-conditions to existing MA message rules in the same procedure. The messages are now rejected if the train has an emergency stop from the RBC.

There is a new procedure to send the Acknowledgement of emergency stop message out.

Changes Laurent made to the checker are in this pull request, too. It now checks that a variable's default value has the same type as the variable.