rename the package to chores

[simonpcouch]

Closes #83. Also taking this as an opportunity to clarify the grammar of the package; "a pal from the pal package with a given role" would now read "a helper from the chores package for a given chore."

• The name of the package: pal -> chores
• The name of the object: pal -> helper (or "chore helper" if it's ambiguous)
• The word for the task being done: role -> chore

A log of the automated replacements

"pal package" -> "chores package"
"pal addin" -> "chores addin"
"pal environment" -> "chores environment"
"pal gallery" -> "chores gallery"

list_pals -> list_helpers
"The [something] pal" -> "The [something] helper"
pal_something -> cli_helper (note the order switch)
"the pal" -> "the helper"

" pals" -> " helpers"

Manually update "pal's" to "chores'" or "helper's"

pal_dir -> chores_dir
pal_env -> chores_env
pal_chat -> chores_chat
pal_app -> chores_app
pal_ -> helper_
.init_pal -> .init_helper
retrieve_pal -> retrieve_helper
_pal -> _helper

Replacing "pal" itself was quite tricky, as "chore" or "chores" or "helper" could all be valid, depending on the situation. I just did a Find, then manually did everything that wasn't "chores", then did a Find and Replace.

For roles:
"with role" -> "for chore"
"has the role" -> "is for the chore"
"with the role" -> "for the chore"
"roles" -> "chores"
"role" -> "chore"