This commit introduces ErrorReporter, a utility class which consolidates
all of the error logging functionality into a common set of functions.
It also replaces all direct interactions with an ErrorList with calls to
an ErrorReporter.
This commit resolves issue #2209
This commit adds support for a standard do <statement> while <expr>;
form of statement. While loops were already being supported; supporting
a do/while loop mostly involves reusing code from while loops but putting
the conditional checking last.
