Tick off "Investigate need for 'final'"

[henrikt-ma]

According to today's web meeting, I'm setting up this PR for documenting why we're ticking off this item on the road map.

All occurrences of final in the https://github.com/modelica/ModelicaSpecification/blob/MCP/0031%2Beliminate-final/RationaleMCP/0031/grammar.md, and things that have made this possible include:

• Flat Modelica describes a state of affairs where all checking for modifications that violate final should have taken place during reduction from full Modelica to Flat Modelica.
• One thing one cannot check during reduction to Flat Modelica is that a final modification of start in full Modelica won't be modified at the time of simulation initialization. For this we needed something else in Flat Modelica, and we now instead have the new parameter equations that allows expressing that something can be modified at the time of initialization. That is, to express that the original Full Modelica modification of start was final, one should simply use a normal initial equation instead of a parameter equation.

Borrowing examples from https://github.com/modelica/ModelicaSpecification/blob/MCP/0031%2Beliminate-final/RationaleMCP/0031/differences.md:

  Real 'x';
  parameter equation guess('x') = 1.5; /* Coming from Full Modelica non-final modification of 'start'. */
  Real 'y';
initial equation
  guess('y') - 1.5 = 0; /* Coming from Full Modelica final modification of 'start'. */

[olivleno]

Web Meeting: (Hans, Martin, Gerd, Kai, Henrik, Oliver)
approved