In quarry, skip past undiggable nodes

The quarry used to get stuck when it encountered an undiggable node.
Change it to skip past that node, digging whatever later stuff it can.
Necessarily, the current digging position becomes semantically-significant
state: it is no longer sufficient to search the quarry cuboid from the top
on each iteration.  The current digging height is reported in the quarry's
interaction form, and can be reset to the top using a button on the form.

Where there is a non-air node within the quarry directly above the
next node to dig, it blocks the quarry's access to that node, even if
everything involved is diggable.  Thus an undiggable node casts a shadow
of undug nodes below it.  Resolving undiggability of a node is a major
reason to use the restart button.
Smoother link of processing cycles to ABM cycles

Make the generic processing machine code willing to complete more than
one processing cycle in one ABM cycle, and more generally to carry
over leftover processing effort after completing a processing cycle.
The src_time meta item now represents accumulated processing effort
(time multiplied by speed) in a scaled form (to retain fractions),
rather than just time in integral seconds.  This affects the MV furnace,
with speed 4 and most recipe times being 3 s, and will be essential for
faster furnaces.
Tube capability for tool workshop

Tool workshop can now accept tools to repair via tube.  It has upgrade
slots.  Battery upgrade reduces its power consumption.  Tube upgrade
makes it eject fully-repaired (or unrepairable) items via tube.