Enhancement: Hammer keyvalues copy/paste (but in the actual clipboard) #1729
Description
What would this enhancement be for?
Hammer
Describe your enhancement suggestion in more detail
When you open the Object Properties window for an entity in Hammer, you are given the options to Copy and Paste the keyvalues. However, what it currently does is replace all the keyvalues (and class) of an entity, preserving its origin and orientation only. Moreover, it uses an internal clipboard, so copied keyvalues can't be pasted outside of Hammer.
This system should actually copy the keyvalues to the user's system clipboard, in a readable format (preferably KV3), that they can then edit in a text editor if they choose to. Moreover, the system should allow pasting from the system clipboard, so users can define presets or use modified data.
Ideally, this should only replace data that is defined in the keyvalues, leaving unspecified keyvalues untouched. For example, if a user copies the data, then modifies it so that most keyvalues are removed except for, let's say, model and color, then pasting should keep all the original entity's data intact and only replace its model and color. This should also be compatible cross-class, so similar entity structures can exchange data.
For further extensions and improvements of this system, it could also allow users to independently copy keyvalues, or check/uncheck which items to copy. It'd also be helpful if it didn't copy the entity class by default – or at the very least give the user the option to choose. This would also fit neatly with issue #1620 , specifically point 1, where users may want to copy data from the Clustered Light Inspector onto Hammer.