This fixes 43c8d0b5.

This reapplies commit ddcb5001,
now that we have no more unexpected success.

This test was fixed by commit df7ee3a3
("specialise should be copied into Delivery instead of Movement in PL builder").

Use only one global RenderJs variable to access different modules instead of many global variable here and there.

Use scope and closures to make all gadget module alike.

Add a test about checking quantity unit behavior on movement. Quantity unit set to movement must not be changed by changing default quantity unit on resource. This test will fail as expected.

add new assert to support range of values expected. The position is calculated on planning box and is returning small difference on value in each testnode result. With this, the test was changed to support this range.

TIDStorage monkey-patches ZEO so it imported it before 'custom_zodb' is loaded.
This commit fix 'custom_zodb' to reset ZEO triggers.

This revert a wrong change in commit 8995b645

Move active context creation, active callable creation, packet length test
out of loop.

That change makes no sense latency-wise, iteration will anyway happen
inside "list()". Also, it potentially degrades memory usage.

use key press instead of click on button save to avoid permission denied failure with selenium and firefox

Reduce differences between similar tests.
Remove bit-rot comments.
Simplify code (avoid redundant lookups, ...).
Also, make easier to subclass and use for a different category tree.

Still, don't fail depending on day of week.