Fix cstring input length interpretation issue that had a buffer overflow case.
The cases added to the manipulatorsInput test are runnable against an old libcfa build. In this setup, the test fails with an illustration of the bug.
The testing in this commit drives the following inputs through a length-8 buffer.
The obviously-missing cases, like 1234567, will be added later. They will accompany fixes for further bugs not solved yet.