[RFC] Improved Subtest-bypass control

[cevich]

In 0.7.x we have a disabled CSV list that can be more or less hard-coded to force subtests and sub-subtests to raise TestNAError. However this is exploiting faulty logic (this exception is suppose to be a signal for environment or pre-requesite problems). The central issue is we have no access to read from configuration within the control file, and no existing way to pass information from control into subtests.

One possible way we can resolve this, is if the control file is given write-only access to record informational/advisory values into a dedicated config. file. In other words, every time the harness runs, control could write a new config_custom/control.ini. This could then be consulted by subtests/sub-subtests to consider appropriate action.

[cevich]

dang, in fact, we can't have control write config_custom/control.ini because test-skipping needs to happen via exclusion from the steps engine. So it really does all have to happen inside the control file, and not interact with subtest config at all 😖

[cevich]

To address #114, one idea might be to use a special character like "~" to invert meaning of --args. i.e. skip the listed tests instead of run only listed tests.

[cevich]

This issue has been resolved by extending --args processing to include two new tokens: 'i=' and 'x=' to specify specific sub/sub-subtests to include or xclude. This was really difficult to pull off and required extending not only the control file but many aspects of the Subtest, SubSubtest, and SubSubtestCaller classes. One nice side-effect is that it's now possible for SubSubtestCaller's to dynamically generate their own subsubtests at module-load time. All of this is in #109