Strategy for consistently reporting design inconsistency

[tomcl]

One of the key selling points of Issie is that design errors should be very well highlighted with error messages that explain and tell the user how to correct the error, with details.

With the addition of parameters to subsheets, and when working on very large designs, more care is needed in how to do this.

Currently CanvasStateAnalyser and SimulationGraphAnalyser do most of the checking, returning a SimulationError option.

1. This error type should be extended with extra info and used for design and simulation errors
2. It should be able to identify components in any sheet (not just top-level)
3. It should be able to include parameter violations (e.g. a constant too large for its bus width) with good error messages
4. Parameter violations that are not direct (could be mended by changing sheet-level parameters) should be reported as warnings when set in property boxes and errors when simulated - at this point parameters are all known.
5. Parameter violations due to chained parameters should accurately report the chain
   • A chain is when a sheet parameter is fed to a subsheet and used there.

To implement this strategy all errors should be refactored, many improved, and error reporting made graduated (with warnings) and better (with clearer identification of errors) throughout.

This discussion is linked to #157