Add code/While, a few tests for the "while" statement
Add copyright header to test files
Add code/For, some tests for the "for" statement
For/While: Add continue/break test cases
code/Rule: Test cases for rule definition/invocation
UserRuleInstructions: Fix setting parameter variables

* The number variables were off by one, since they are 1 based.
* The '<' and '>' variables were missing.
DataBasedTest[Parser]: Add directive "#!skip"

* "#!skip" accepts arguments similar to "#!compat" (save for "!ham") and
  has more or less the inverse meaning. Jam/Ham versions specified won't
  even run the test.
* Adjust RunnableTest/DataBaseTest::TestCaseCompatibility() to return
  the skip mask via reference parameter.
* Adjust TestRunner::_RunTestCase() to evaluate the skip mask.
code/Rule: Add some "return" tests
UserRuleInstructions(): Reset return jump condition
DataBasedTest -> TemplateBasedTest
DataBasedTestParser: Simplify directive parsing

Let _ReadLine() parse the directive name already, so we don't need to do
that whereever we need directive arguments.