unify new/free() functions 1

unify new/free() functions 1

- Name ends in `_free()`
- Take a `**ptr`
- Creates a native pointer
- Sets pointer to `NULL`

Functions changed:
- cs_free()
- mailcap_entry_free()
- mutt_addr_free()
- mutt_alias_free()
- mutt_alias_new()
- mutt_body_free()
- mutt_enter_state_free()
- mutt_env_free()
- mutt_seqset_iterator_free()
- nntp_edata_free()
- query_free()
- remailer_free()
- remailer_new()