Chat histories should not be saved in .cache directory

[tlbgr]

To upvote this issue, give it a thumbs up. See this list for the most upvoted issues.

Describe the bug

All chat histories are saved under $HOME/.cache/eca, but by the XDG standard, the cache directory is supposed to hold non-essential (cached) data, i.e. data that can be regenerated. This is clearly not the case for the eca chat history storage. To my understanding, I should not lose any data when I delete the .cache directory.
See e.g.: https://specifications.freedesktop.org/basedir/latest/

To Reproduce

Run eca through e.g. eca-emacs.

Expected behavior

Chat history should be stored for example under .local/share.

[ericdallo]

Hum, interesting, I wonder where we should storage tho? and if we change that we will need to make it backwards compatible of course
c/c @zikajk

[tlbgr]

I think $XDG_DATA_HOME would be the canonical place (defaults to $HOME/.local/share).
Not sure about backwards compatibility.