test/webapp/base-framework.php: Fix typo in comment.
src/webapp/base-framework.php: Factor call to 'session_start' into protected method ('sessionStart') to allow for overriding of this particular function call for testing purposes (allowing us to do slightly "deeper" testing of request-handling process -- as calling 'session_start' more than once in the same PHP process/thread will cause PHP to crap out); and, make method 'outputHttpResponse' protected, as well, also allowing for overriding to be used to avoid test-cases dumping real output.
test/webapp/harness.php: When dispatching mock HTTP requests, perform "deeper" testing by calling 'go' method of FrontController (same as that which should be used for real-world apps), stubbing out 'sessionStart' and 'outputHttpResponse' appropriately.
src/webapp/base-framework.php: Properly call 'warn' method of FrontController when illegal session-ID is provided (rather than undefined global 'warn' function); relevant test-case included.