Fixes renwick shield generators incorrectly using power

- Shield generators now correctly use power according to actual field strength.
- Minimal shield dissipation rate now corresponds with 1 renwick field (changed from 10, which technically caused shields to always use max upkeep power ignoring field strength completely)
Canister Logs

Opening a non-empty canister now produces an admin message, not only a log note on the canister itself.
Fixes #7061
Fixed a bug that made it impossible for AIs to change air alarm sensor settings
Merge pull request #7067 from PsiOmegaDelta/TheGlassShuttle

Fixes #7061
Merge pull request #7070 from Amunak/airalarm-fix2

fixed a bug that made it impossible for AIs to change air alarm sensor settings
Fixes missing icons for xenoarchaeology items EXCEPT for the energy guns.
Fixes the xenoarch eguns.

This was done by making the xenoarch eguns new subtypes with different update_icon() procs than the regular eguns. The new subtypes are in finds_eguns.dm
Fixes a bug where core samplers dispensed bags that you could not take rock slivers out of.
Merge pull request #7077 from MagmaRam/bugfix

Fixes xenoarch find sprites and core samplers not working
Merge pull request #7064 from PsiOmegaDelta/CanisterLogs

Canister Logs
Merge pull request #7055 from atlantiscze/dem-shields

Fixes renwick shield generators incorrectly using power
Merge pull request #1 from Baystation12/master

Merge