This reverts commit 14234ccce3e7eec1153e810fab75afb2e90a2b22.

WallclockTime is set at the time a message is created. Since messages
can be placed in queues before being rendered, this is not always
the same time as the wallclock time when rendering the message, so it
needs to be stored in the message.

widget.py: Add the two new widgets
_message.py: record system time when a message is created.

The idea of a sequence number/ID is to tie together all messages
associated with a given timed activity, to make performance
analysis easier.

_context.py: Add sequence number with atomic increment
_widget.py: SequenceID widget, which displays this value
_message.py: sequence_id variable storing the sequence for a message.

To differentiate between the element and the task, some messages come
from an element that is not the primary element of the task (i.e.
when running integration commands on behalf of another element)

To handle the unhandled exceptions and report them to the
frontend as bugs.

Warnings and errors should be displayed even if silence
was requested for their depth.

Allow propagation of the build sandbox back to the main process.