Support "strict" mode to disable ignore directives

[e-shreve]

Support an argument and per-rule setting to disable ignore via line comments (strict mode).
(Consider and document what will happen if a rule is ignored via the hash lookup method. Maybe also disable that method as well for strict mode, or print warning, or do nothing?)

[e-shreve]

Note: Need to update the code to pass a Rule object around instead of just the rule's name as a string. That way classes like the IgnoreFilter can check to see if a Rule is in "strict" mode.

Also, should add a setter to the Rule class so rule authors can write rules that default to strict mode. Open question: if an author does this, should their setting overrule a config file setting strict to off for the rule? Might need to support both. Although if supporting both, then the documentation for users might be confusing as not all rules will operate the same way.