Security: Missing range checks on comment processing.

Security: Missing range checks on comment processing.

The fss_payload_read such as the runtime test is wrong:
  # fss_payload_read -ocn payload level_3/fss_read/tests/runtime/fss_000e/source/test-0002-mixed.fss -t

The output is 1 but should instead be 4.
  # fss_payload_read -ocn payload level_3/fss_read/tests/runtime/fss_000e/source/test-0002-mixed.fss | wc -l

Investigating this problem revealed that the comment handling code is failing to perform a range check.
The overflow is causing the stop range to point to some random memory address which is almost always larger than the file.
This results in the count being wrong.

This bug is a security concern.
Add the range check in all places where this range check is missing for the comments.

Add additional runtime tests to reflect the condition that exposed this issue.
There is now a "payload" test for all runtime tests.

Update the testfile to make manually generating and verifying the runtime tests easier.
The "generate" and "verify" fakefile operations could not be directly called due needing additional data setup.
Also expose the "test-" setting as a parameter to make changing it easier.