Feature Request - Be able to put a GK into "Parked" / "Released" mode

Related to https://github.com/geokrety/geokrety-api/issues/26

Description

This feature should allow owner to set a parked flag on individuals GK. Once a GK has this flag set to True, the current holder cannot be changed. When a GK is parked, it won't appear anymore in holder's inventory, all users will only have logtypes Write Note or discover available. It should be possible for the holder to move it back in his inventory ("Release") by deleting the associated log in the GK page. The link used to "park" the GK can be of type toggle. It is possible to park a GK only when it is in owner inventory.

Logic table

parked	holder	log types available
FALSE	any	ALL
FALSE	holder	ALL
TRUE	any	WRITE COMMENT + DISCOVER
TRUE	holder	WRITE COMMENT + DIPPED + ARCHIVE

Implementation

Internal database representation

One new fields should be added to the GK table. Let's say parked.

Pages upgrade

The following pages must be adapted:

• ruchy.php
• konkret.php
• szukaj-ajax.php
• funkcje.js
• aktualizuj.php

Note: We should take care of the SQL request using to compute the hand_of field. If a GK is parked then, hand_of must have value of owner_id.

User eXperience

• Parked status should be visible on the GK "description zone".
• Parked status should be visible in the GK move history as a log entry.
• On the GK page, in the tools section, there should be a dedicated link to the feature.
• On the GK page, the same link could be used as a toggle (Parked/Released).
• Owner can delete the parked log entry to release the GK.
• On the move page, the log type list should be dynamically updated to reflect the rules.

Related ideas

• allow a "coordinate less" log of the type "discovered somewhere in the hands of the owner".