src/template/variable-scope.php: Remove no-longer-relevant TODO comment.
test/template/: Move 'renderAndNormalize' and 'normalizeSpace' functions from basic.php to new file, helpers.php, to make these helper-functions available to rest of template test suite.
src/error-handling.php: Break calls to 'set_error_handler' and 'set_exception_handler' into separate functions so the error and/or exception handler can be enabled (independently or together) at will.
test/test.php: Enable error-handler when running test suite, so exception will be raised for any PHP notices/warnings/errors.
test/template/helpers.php: Add helper-function 'renderAndNormalizeTplFile'.
src/template/: Add support for "blocks" that accept parameters, including a sort-of temporary hack to distinguish between local variables (including function/block parameters) and "template variables" (variables that should receive their values from those passed into the template rendering functions (renderString, renderFile).