Error/warning identification strings

[ehkropf]

I would like to standardise the use of the identification strings used when calling error and warning. I have in use currently

• CMT:InvalidArgument
• CMT:NotDefined
• CMT:OutOfTolerance
• CMT:NotImplemented
• CMT:BadIdea
• CMT:BadThings

Admittedly the last two need rethought.

I'm thinking that if we keep this to a manageable list, it is easer for user code to look for errors from our code specifically, e.g., in try/catch blocks. A bit like we use MATLAB:UndefinedFunction in conformalmap for instance. Using identification strings along the lines of CMT:class:function seems to duplicate the work of the default error handler, as a console error tells you in which file the error originated.