decision: the base for any deadline calculations
is the expected real time corresponding to the grid origin.
This value is contained in the Timings record.
this clarifies the relation of TimeAnchor and Timings,
the latter act as a general spec and abstracted grid,
while the latter actually performs the conversion and
deadline checking
instead of (ab)using the Timings spect for a
runtime switch, better use the existing
MockInjector facility and thus turn the
mock engine mode into a global switch